| Author | Messages | |
FreddyHARTONO
Posts:19
 | | 12/09/2005 12:45 PM |
| Hi All
Was just trying to understand something and am getting conflicting results..
If I set the following (or 2 mx of the same priority with 2 differnet a records)
Mydomain.com MX 10 mail.mydomain.com
Mail.mydomain.com A 10.1.1.1
Mail.mydomain.com A 10.2.2.2
I understand that will provide dns roundrobin but what happened if I shutdown 10.2.2.2, will I lose (logically) 50% of my mail as I do not have another fallback MX??
My understanding is that it does so as the sender mail server will cache the MX record and A record and will only send to there, am I right or am I getting this wrong?
If I'm shutting down 10.2.2.2, will the sender mail server retries to 10.1.1.1? (lets assume there's no ttl reconfig to zero)
Thanks lots
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785 | | | |
| michael@xxxx.yyy
| | 12/09/2005 12:54 PM |
| You
should have two separate MX records
@ IN MX 10 mail1.mydomain.com.
@ IN MX 10 mail2.mydomain.com.
Mail1 IN A 10.1.1.1
Mail2 IN A 10.2.2.2
RFC
2821 requires a mail server to choose MX records randomly when the records are
the same priority, but to try all if the initial one chosen doesn™t work
(until it finds one that does work or the pool is exhausted).
Your
proposal below has the problem you describe.
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Freddy HARTONO
Sent: Friday, December 09, 2005 7:43 AM
To: activedir@xxxxxxxxxxxxxxxxxx
Subject: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi All
Was just trying to
understand something and am getting conflicting results..
If I set the following (or
2 mx of the same priority with 2 differnet a records)
Mydomain.com
MX
10 mail.mydomain.com
Mail.mydomain.com
A
10.1.1.1
Mail.mydomain.com
A
10.2.2.2
I understand that will
provide dns roundrobin but what happened if I shutdown 10.2.2.2, will I lose
(logically) 50% of my mail as I do not have another fallback MX??
My understanding is that it
does so as the sender mail server will cache the MX record and A record and
will only send to there, am I right or am I getting this wrong?
If I'm shutting down
10.2.2.2, will the sender mail server retries to 10.1.1.1? (lets assume there's
no ttl reconfig to zero)
Thanks lots
Thank you and have a
splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785 | | | |
| FreddyHARTONO
Posts:19
| | 12/10/2005 3:11 AM |
| Hi Michael
Thanks for the quick reply.
RFC 2821 requires a
mail server to choose MX records randomly when the records are the same
priority, but to try all if the initial one chosen doesn™t work (until it finds
one that does work or the pool is exhausted).
The above means it will try MX of other priorities
right (not the other of the same priorities correct?) - sorry just not having a
clear word by word answer in the RFC document itself.
One of my vendor is giving me a whitepaper from
barracuda appliance that explains how its done, but mentioned that with MX
listing below it will provides load balancing AND redundancy (crap to me but now
im getting confused myself)
http://www.barracudanetworks.com/ns/downloads/Barracuda_WP_MX_Load_Balancing.pdf
Is it recommended that the TTL for the domain be set to
0 when using this MX load balancing method?
Thank you and have a splendid
day!
Kind Regards,
Freddy Hartono
Group Support
Engineer InternationalSOS Pte Ltd mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65)
6330-9785
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Michael B.
SmithSent: Friday, December 09, 2005 8:52 PMTo:
ActiveDir@xxxxxxxxxxxxxxxxxxSubject: RE: [ActiveDir] [Way OT] DNS MX
load balancing questions...
You should have two
separate MX records
@
IN
MX
10
mail1.mydomain.com.
@
IN
MX
10
mail2.mydomain.com.
Mail1
IN
A
10.1.1.1
Mail2
IN
A
10.2.2.2
RFC 2821 requires a
mail server to choose MX records randomly when the records are the same
priority, but to try all if the initial one chosen doesn™t work (until it finds
one that does work or the pool is exhausted).
Your proposal below has
the problem you describe.
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Freddy
HARTONOSent: Friday, December 09, 2005 7:43 AMTo:
activedir@xxxxxxxxxxxxxxxxxxSubject: [ActiveDir] [Way OT] DNS MX load
balancing questions...
Hi All
Was just trying to
understand something and am getting conflicting results..
If I set the following (or
2 mx of the same priority with 2 differnet a records)
Mydomain.com
MX
10 mail.mydomain.com Mail.mydomain.com
A
10.1.1.1 Mail.mydomain.com
A
10.2.2.2
I understand that will
provide dns roundrobin but what happened if I shutdown 10.2.2.2, will I lose
(logically) 50% of my mail as I do not have another fallback
MX??
My understanding is that it
does so as the sender mail server will cache the MX record and A record and will
only send to there, am I right or am I getting this wrong?
If I'm shutting down
10.2.2.2, will the sender mail server retries to 10.1.1.1? (lets assume there's
no ttl reconfig to zero)
Thanks lots
Thank you and have a
splendid day!
Kind Regards,
Freddy Hartono
Group Support
Engineer InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65)
6330-9785 | | | |
| deji
Posts:132
| | 12/10/2005 4:33 AM |
| >>> RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Correct. There was, however, an issue early this year (or was it late last
year?) where 2K3 SMTP servers were failing to fail over to the next available
SMTP servers on the list they receive from a target DNS server. I think this
was corrected with a hotfix, but the issue will still exist in a gold,
un-hotfixed version.
>>>The above means it will try MX of other priorities right (not the other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
It will continue to use the highest one, until that one stops responding. As
long as the highest-prioritized one continues to accept emails, the
originating server will have no need to try another one.
HTH
Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCT
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about
Yesterday? -anon
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of Freddy HARTONO
Sent: Sat 12/10/2005 7:07 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi Michael
Thanks for the quick reply.
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
The above means it will try MX of other priorities right (not the other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
One of my vendor is giving me a whitepaper from barracuda appliance that
explains how its done, but mentioned that with MX listing below it will
provides load balancing AND redundancy (crap to me but now im getting
confused myself)
http://www.barracudanetworks.com/ns/downloads/Barracuda_WP_MX_Load_Balancing.
pdf
Is it recommended that the TTL for the domain be set to 0 when using this MX
load balancing method?
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Michael B. Smith
Sent: Friday, December 09, 2005 8:52 PM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
You should have two separate MX records
@ IN MX 10 mail1.mydomain.com.
@ IN MX 10 mail2.mydomain.com.
Mail1 IN A 10.1.1.1
Mail2 IN A 10.2.2.2
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Your proposal below has the problem you describe.
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Freddy HARTONO
Sent: Friday, December 09, 2005 7:43 AM
To: activedir@xxxxxxxxxxxxxxxxxx
Subject: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi All
Was just trying to understand something and am getting conflicting results..
If I set the following (or 2 mx of the same priority with 2 differnet a
records)
Mydomain.com MX 10 mail.mydomain.com
Mail.mydomain.com A 10.1.1.1
Mail.mydomain.com A 10.2.2.2
I understand that will provide dns roundrobin but what happened if I shutdown
10.2.2.2, will I lose (logically) 50% of my mail as I do not have another
fallback MX??
My understanding is that it does so as the sender mail server will cache the
MX record and A record and will only send to there, am I right or am I
getting this wrong?
If I'm shutting down 10.2.2.2, will the sender mail server retries to
10.1.1.1? (lets assume there's no ttl reconfig to zero)
Thanks lots
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ | | | |
| FreddyHARTONO
Posts:19
| | 12/11/2005 1:43 AM |
| Hi Deji
Thanks for the replies
That means it makes no sense to invest in having 1 backup MX of lower
priorities?
So basically what I need is as below?
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 10 mail3.mydomain.com
Instead of
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 100 mail3.mydomain.com?
Since with all 3 of the same priorities, if any of the mail is down (mail2)
for example, it will retry to mail1 and mail3 automatically according to
RFC?
Do you happen to have the KB of the exchange issue mentioned below, just
wanted to readup on that bug somehow :)
Basically we're trying to purchase spam/virus gateways in front of exchange,
and I had the idea that it needs to be 3 appliances (2 for load balancing, 1
for backup).
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
-----Original Message-----
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of deji@xxxxxxxxxxxxxx
Sent: Sunday, December 11, 2005 12:31 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
>>> RFC 2821 requires a mail server to choose MX records randomly when
>>> the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Correct. There was, however, an issue early this year (or was it late last
year?) where 2K3 SMTP servers were failing to fail over to the next
available SMTP servers on the list they receive from a target DNS server. I
think this was corrected with a hotfix, but the issue will still exist in a
gold, un-hotfixed version.
>>>The above means it will try MX of other priorities right (not the
>>>other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
It will continue to use the highest one, until that one stops responding. As
long as the highest-prioritized one continues to accept emails, the
originating server will have no need to try another one.
HTH
Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCT
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about
Yesterday? -anon
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of Freddy HARTONO
Sent: Sat 12/10/2005 7:07 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi Michael
Thanks for the quick reply.
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
The above means it will try MX of other priorities right (not the other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
One of my vendor is giving me a whitepaper from barracuda appliance that
explains how its done, but mentioned that with MX listing below it will
provides load balancing AND redundancy (crap to me but now im getting
confused myself)
http://www.barracudanetworks.com/ns/downloads/Barracuda_WP_MX_Load_Balancing
.
pdf
Is it recommended that the TTL for the domain be set to 0 when using this MX
load balancing method?
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Michael B. Smith
Sent: Friday, December 09, 2005 8:52 PM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
You should have two separate MX records
@ IN MX 10 mail1.mydomain.com.
@ IN MX 10 mail2.mydomain.com.
Mail1 IN A 10.1.1.1
Mail2 IN A 10.2.2.2
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Your proposal below has the problem you describe.
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Freddy HARTONO
Sent: Friday, December 09, 2005 7:43 AM
To: activedir@xxxxxxxxxxxxxxxxxx
Subject: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi All
Was just trying to understand something and am getting conflicting results..
If I set the following (or 2 mx of the same priority with 2 differnet a
records)
Mydomain.com MX 10 mail.mydomain.com
Mail.mydomain.com A 10.1.1.1
Mail.mydomain.com A 10.2.2.2
I understand that will provide dns roundrobin but what happened if I
shutdown 10.2.2.2, will I lose (logically) 50% of my mail as I do not have
another fallback MX??
My understanding is that it does so as the sender mail server will cache the
MX record and A record and will only send to there, am I right or am I
getting this wrong?
If I'm shutting down 10.2.2.2, will the sender mail server retries to
10.1.1.1? (lets assume there's no ttl reconfig to zero)
Thanks lots
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ | | | |
| AD000001348
Posts:0
| | 12/11/2005 2:11 AM |
| Depends on what you want to accomplish. Keep in mind the purpose of what
you're doing and what you're dealing with.
If you want to ensure that you have published mail handlers in a way that
those that want to communicate with you can understand with a goal of having
high availability, then you would want to identify the lowest common
denominator of client and appeal to that. 2821 may not be what you want.
821 might be a little more in line with what you're trying to accomplish.
Depends on what's out there trying to communicate with you and the
understanding that client has of your mail handlers.
Using MX records of equal weight would give you pretty good results in most
situations. You may want to prioritize differently if you had several mail
handlers of different capabilities. For example, if you had a MTA that was
on a lower class of hardware (and therefore couldn't handle the same volume)
you might want it to be there as a last resort handler. Your other two
MTA's are the same and similarly connected so you would prioritize them the
same (most likely).
In your case, I'd use multiple MX records and I would weight the same since
you only have two. As long as when a failure occurs it's enough to trigger
the sending MTA to try other records you'll not interrupt mail flow.
Additionally, since SMTP is a store and forward protocol, you won't
interrupt mail flow as long as you put the MTA back in service in a
reasonable amount of time (seems like some are using 24 hours as the amount
of time to queue mail so it seems reasonable to put the MTA back in service
w/in that time frame).
DNS RR's with a zero TTL are just plain rude when used for everyday usage,
but they can be useful when making changes on your network. I haven't read
that pdf yet, but should be interesting to see the context.
Al
From: Freddy HARTONO
Reply-To: ActiveDir@xxxxxxxxxxxxxxxxxx
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Date: Sun, 11 Dec 2005 09:40:58 +0800
Hi Deji
Thanks for the replies
That means it makes no sense to invest in having 1 backup MX of lower
priorities?
So basically what I need is as below?
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 10 mail3.mydomain.com
Instead of
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 100 mail3.mydomain.com?
Since with all 3 of the same priorities, if any of the mail is down (mail2)
for example, it will retry to mail1 and mail3 automatically according to
RFC?
Do you happen to have the KB of the exchange issue mentioned below, just
wanted to readup on that bug somehow :)
Basically we're trying to purchase spam/virus gateways in front of
exchange,
and I had the idea that it needs to be 3 appliances (2 for load balancing,
1
for backup).
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
-----Original Message-----
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of
deji@xxxxxxxxxxxxxx
Sent: Sunday, December 11, 2005 12:31 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
>>> RFC 2821 requires a mail server to choose MX records randomly when
>>> the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Correct. There was, however, an issue early this year (or was it late last
year?) where 2K3 SMTP servers were failing to fail over to the next
available SMTP servers on the list they receive from a target DNS server. I
think this was corrected with a hotfix, but the issue will still exist in a
gold, un-hotfixed version.
>>>The above means it will try MX of other priorities right (not the
>>>other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
It will continue to use the highest one, until that one stops responding.
As
long as the highest-prioritized one continues to accept emails, the
originating server will have no need to try another one.
HTH
Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCT
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about
Yesterday? -anon
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of Freddy HARTONO
Sent: Sat 12/10/2005 7:07 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi Michael
Thanks for the quick reply.
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
The above means it will try MX of other priorities right (not the other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
One of my vendor is giving me a whitepaper from barracuda appliance that
explains how its done, but mentioned that with MX listing below it will
provides load balancing AND redundancy (crap to me but now im getting
confused myself)
http://www.barracudanetworks.com/ns/downloads/Barracuda_WP_MX_Load_Balancing
.
pdf
Is it recommended that the TTL for the domain be set to 0 when using this
MX
load balancing method?
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Michael B. Smith
Sent: Friday, December 09, 2005 8:52 PM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
You should have two separate MX records
@ IN MX 10 mail1.mydomain.com.
@ IN MX 10 mail2.mydomain.com.
Mail1 IN A 10.1.1.1
Mail2 IN A 10.2.2.2
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Your proposal below has the problem you describe.
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Freddy HARTONO
Sent: Friday, December 09, 2005 7:43 AM
To: activedir@xxxxxxxxxxxxxxxxxx
Subject: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi All
Was just trying to understand something and am getting conflicting
results..
If I set the following (or 2 mx of the same priority with 2 differnet a
records)
Mydomain.com MX 10 mail.mydomain.com
Mail.mydomain.com A 10.1.1.1
Mail.mydomain.com A 10.2.2.2
I understand that will provide dns roundrobin but what happened if I
shutdown 10.2.2.2, will I lose (logically) 50% of my mail as I do not have
another fallback MX??
My understanding is that it does so as the sender mail server will cache
the
MX record and A record and will only send to there, am I right or am I
getting this wrong?
If I'm shutting down 10.2.2.2, will the sender mail server retries to
10.1.1.1? (lets assume there's no ttl reconfig to zero)
Thanks lots
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ | | | |
| deji
Posts:132
| | 12/11/2005 4:02 AM |
| In the first scenario, all 3 servers CAN be used at any time. In the second
scenario, mail3 will be used ONLY if mail1 and mail2 stop responding.
Scenario 1 balances the load (not evenly, mind you) across the 3 servers.
Keep in mind that the "balancing" act only means that IF 3 external servers
asks for your MX, they will see that all 3 are of equal weight and MAY choose
any one of the 3 to send to. In an ideal world, externalserver1 will choose
mail1, externalserver2 will choose mail2 and externalserver3 will choose
mail3 and the load will be truly balanced. Well, we are not there yet. In
reality, nothing stops all 3 external servers from sending to mail1 or mail2
all at the same time.
Also, bear in mind that, although you have 3 equally-weighted MX, an external
server will choose one of the 3 and continue to send to that chosen one until
that one stops responding. The fact that you have 3 equally-weighted servers
does not mean that the external server will use each of them equally or
sequentially.
Wrt the issue I mention, it is NOT an Exchange problem per se. It is an MS
SMTP issue. Here's a reference
http://support.microsoft.com/default.aspx?scid=kb;en-us;837993. Can't find a
more detailed discussion of it at this time.
Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCT
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about
Yesterday? -anon
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of Freddy HARTONO
Sent: Sat 12/10/2005 5:40 PM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi Deji
Thanks for the replies
That means it makes no sense to invest in having 1 backup MX of lower
priorities?
So basically what I need is as below?
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 10 mail3.mydomain.com
Instead of
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 100 mail3.mydomain.com?
Since with all 3 of the same priorities, if any of the mail is down (mail2)
for example, it will retry to mail1 and mail3 automatically according to
RFC?
Do you happen to have the KB of the exchange issue mentioned below, just
wanted to readup on that bug somehow :)
Basically we're trying to purchase spam/virus gateways in front of exchange,
and I had the idea that it needs to be 3 appliances (2 for load balancing, 1
for backup).
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
-----Original Message-----
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of deji@xxxxxxxxxxxxxx
Sent: Sunday, December 11, 2005 12:31 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
>>> RFC 2821 requires a mail server to choose MX records randomly when
>>> the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Correct. There was, however, an issue early this year (or was it late last
year?) where 2K3 SMTP servers were failing to fail over to the next
available SMTP servers on the list they receive from a target DNS server. I
think this was corrected with a hotfix, but the issue will still exist in a
gold, un-hotfixed version.
>>>The above means it will try MX of other priorities right (not the
>>>other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
It will continue to use the highest one, until that one stops responding. As
long as the highest-prioritized one continues to accept emails, the
originating server will have no need to try another one.
HTH
Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCT
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about
Yesterday? -anon
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of Freddy HARTONO
Sent: Sat 12/10/2005 7:07 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi Michael
Thanks for the quick reply.
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
The above means it will try MX of other priorities right (not the other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
One of my vendor is giving me a whitepaper from barracuda appliance that
explains how its done, but mentioned that with MX listing below it will
provides load balancing AND redundancy (crap to me but now im getting
confused myself)
http://www.barracudanetworks.com/ns/downloads/Barracuda_WP_MX_Load_Balancing
.
pdf
Is it recommended that the TTL for the domain be set to 0 when using this MX
load balancing method?
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Michael B. Smith
Sent: Friday, December 09, 2005 8:52 PM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
You should have two separate MX records
@ IN MX 10 mail1.mydomain.com.
@ IN MX 10 mail2.mydomain.com.
Mail1 IN A 10.1.1.1
Mail2 IN A 10.2.2.2
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Your proposal below has the problem you describe.
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Freddy HARTONO
Sent: Friday, December 09, 2005 7:43 AM
To: activedir@xxxxxxxxxxxxxxxxxx
Subject: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi All
Was just trying to understand something and am getting conflicting results..
If I set the following (or 2 mx of the same priority with 2 differnet a
records)
Mydomain.com MX 10 mail.mydomain.com
Mail.mydomain.com A 10.1.1.1
Mail.mydomain.com A 10.2.2.2
I understand that will provide dns roundrobin but what happened if I
shutdown 10.2.2.2, will I lose (logically) 50% of my mail as I do not have
another fallback MX??
My understanding is that it does so as the sender mail server will cache the
MX record and A record and will only send to there, am I right or am I
getting this wrong?
If I'm shutting down 10.2.2.2, will the sender mail server retries to
10.1.1.1? (lets assume there's no ttl reconfig to zero)
Thanks lots
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
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| adwulf
Posts:34
| | 12/12/2005 6:14 AM |
| On 12/11/05, Freddy HARTONO wrote:
>
> That means it makes no sense to invest in having 1 backup MX of lower
> priorities?
>
It makes perfect sense to have a backup MX of a lower priority. Most
of your users may be located in New York, so you'd want most of your
mail routed in that way, and would only want the mail server at your
remote site in London to accept mail if NYC was down for some reason.
Your London server might be sitting on a very slow connection to the
outside world, or maybe it's a fairly old machine and not up to
handling high loads, meaning you'd probably only want it to be used in
an emergency.
--
AdamT
"Maidenhead is *not* in Kent"
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ | | | |
| dharris
Posts:0
| | 12/12/2005 7:41 AM |
| Are both (all) of your mailservers at the same location? If so, you can do a better job of load balancing or failover using a router. Cisco IOS lets you fine-tune it pretty well.
-----Original Message-----
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx [mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of deji@xxxxxxxxxxxxxx
Sent: Sunday, December 11, 2005 9:00 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
In the first scenario, all 3 servers CAN be used at any time. In the second scenario, mail3 will be used ONLY if mail1 and mail2 stop responding.
Scenario 1 balances the load (not evenly, mind you) across the 3 servers.
Keep in mind that the "balancing" act only means that IF 3 external servers asks for your MX, they will see that all 3 are of equal weight and MAY choose any one of the 3 to send to. In an ideal world, externalserver1 will choose mail1, externalserver2 will choose mail2 and externalserver3 will choose
mail3 and the load will be truly balanced. Well, we are not there yet. In reality, nothing stops all 3 external servers from sending to mail1 or mail2 all at the same time.
Also, bear in mind that, although you have 3 equally-weighted MX, an external server will choose one of the 3 and continue to send to that chosen one until that one stops responding. The fact that you have 3 equally-weighted servers does not mean that the external server will use each of them equally or sequentially.
Wrt the issue I mention, it is NOT an Exchange problem per se. It is an MS SMTP issue. Here's a reference http://support.microsoft.com/default.aspx?scid=kb;en-us;837993. Can't find a more detailed discussion of it at this time.
Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCT
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about Yesterday? -anon
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of Freddy HARTONO
Sent: Sat 12/10/2005 5:40 PM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi Deji
Thanks for the replies
That means it makes no sense to invest in having 1 backup MX of lower priorities?
So basically what I need is as below?
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 10 mail3.mydomain.com
Instead of
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 100 mail3.mydomain.com?
Since with all 3 of the same priorities, if any of the mail is down (mail2) for example, it will retry to mail1 and mail3 automatically according to RFC?
Do you happen to have the KB of the exchange issue mentioned below, just wanted to readup on that bug somehow :)
Basically we're trying to purchase spam/virus gateways in front of exchange, and I had the idea that it needs to be 3 appliances (2 for load balancing, 1 for backup).
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
-----Original Message-----
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of deji@xxxxxxxxxxxxxx
Sent: Sunday, December 11, 2005 12:31 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
>>> RFC 2821 requires a mail server to choose MX records randomly when
>>> the
records are the same priority, but to try all if the initial one chosen doesn't work (until it finds one that does work or the pool is exhausted).
Correct. There was, however, an issue early this year (or was it late last
year?) where 2K3 SMTP servers were failing to fail over to the next available SMTP servers on the list they receive from a target DNS server. I think this was corrected with a hotfix, but the issue will still exist in a gold, un-hotfixed version.
>>>The above means it will try MX of other priorities right (not the
>>>other of
the same priorities correct?) - sorry just not having a clear word by word answer in the RFC document itself.
It will continue to use the highest one, until that one stops responding. As long as the highest-prioritized one continues to accept emails, the originating server will have no need to try another one.
HTH
Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCT
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about Yesterday? -anon
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of Freddy HARTONO
Sent: Sat 12/10/2005 7:07 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi Michael
Thanks for the quick reply.
RFC 2821 requires a mail server to choose MX records randomly when the records are the same priority, but to try all if the initial one chosen doesn't work (until it finds one that does work or the pool is exhausted).
The above means it will try MX of other priorities right (not the other of the same priorities correct?) - sorry just not having a clear word by word answer in the RFC document itself.
One of my vendor is giving me a whitepaper from barracuda appliance that explains how its done, but mentioned that with MX listing below it will provides load balancing AND redundancy (crap to me but now im getting confused myself)
http://www.barracudanetworks.com/ns/downloads/Barracuda_WP_MX_Load_Balancing
.
pdf
Is it recommended that the TTL for the domain be set to 0 when using this MX load balancing method?
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Michael B. Smith
Sent: Friday, December 09, 2005 8:52 PM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
You should have two separate MX records
@ IN MX 10 mail1.mydomain.com.
@ IN MX 10 mail2.mydomain.com.
Mail1 IN A 10.1.1.1
Mail2 IN A 10.2.2.2
RFC 2821 requires a mail server to choose MX records randomly when the records are the same priority, but to try all if the initial one chosen doesn't work (until it finds one that does work or the pool is exhausted).
Your proposal below has the problem you describe.
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Freddy HARTONO
Sent: Friday, December 09, 2005 7:43 AM
To: activedir@xxxxxxxxxxxxxxxxxx
Subject: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi All
Was just trying to understand something and am getting conflicting results..
If I set the following (or 2 mx of the same priority with 2 differnet a
records)
Mydomain.com MX 10 mail.mydomain.com
Mail.mydomain.com A 10.1.1.1
Mail.mydomain.com A 10.2.2.2
I understand that will provide dns roundrobin but what happened if I shutdown 10.2.2.2, will I lose (logically) 50% of my mail as I do not have another fallback MX??
My understanding is that it does so as the sender mail server will cache the MX record and A record and will only send to there, am I right or am I getting this wrong?
If I'm shutting down 10.2.2.2, will the sender mail server retries to 10.1.1.1? (lets assume there's no ttl reconfig to zero)
Thanks lots
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
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| FreddyHARTONO
Posts:19
| | 12/13/2005 2:50 AM |
| Ah another one of those I wish I had F5 or foundry..nope sadly no have to
rely on the fake load balancing of MX in my case... :)
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
-----Original Message-----
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Derek Harris
Sent: Tuesday, December 13, 2005 3:39 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Are both (all) of your mailservers at the same location? If so, you can do
a better job of load balancing or failover using a router. Cisco IOS lets
you fine-tune it pretty well.
-----Original Message-----
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of deji@xxxxxxxxxxxxxx
Sent: Sunday, December 11, 2005 9:00 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
In the first scenario, all 3 servers CAN be used at any time. In the second
scenario, mail3 will be used ONLY if mail1 and mail2 stop responding.
Scenario 1 balances the load (not evenly, mind you) across the 3 servers.
Keep in mind that the "balancing" act only means that IF 3 external servers
asks for your MX, they will see that all 3 are of equal weight and MAY
choose any one of the 3 to send to. In an ideal world, externalserver1 will
choose mail1, externalserver2 will choose mail2 and externalserver3 will
choose
mail3 and the load will be truly balanced. Well, we are not there yet. In
reality, nothing stops all 3 external servers from sending to mail1 or mail2
all at the same time.
Also, bear in mind that, although you have 3 equally-weighted MX, an
external server will choose one of the 3 and continue to send to that chosen
one until that one stops responding. The fact that you have 3
equally-weighted servers does not mean that the external server will use
each of them equally or sequentially.
Wrt the issue I mention, it is NOT an Exchange problem per se. It is an MS
SMTP issue. Here's a reference
http://support.microsoft.com/default.aspx?scid=kb;en-us;837993. Can't find a
more detailed discussion of it at this time.
Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCT
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about
Yesterday? -anon
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of Freddy HARTONO
Sent: Sat 12/10/2005 5:40 PM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi Deji
Thanks for the replies
That means it makes no sense to invest in having 1 backup MX of lower
priorities?
So basically what I need is as below?
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 10 mail3.mydomain.com
Instead of
Mydomain MX 10 mail1.mydomain.com
MX 10 mail2.mydomain.com
MX 100 mail3.mydomain.com?
Since with all 3 of the same priorities, if any of the mail is down (mail2)
for example, it will retry to mail1 and mail3 automatically according to
RFC?
Do you happen to have the KB of the exchange issue mentioned below, just
wanted to readup on that bug somehow :)
Basically we're trying to purchase spam/virus gateways in front of exchange,
and I had the idea that it needs to be 3 appliances (2 for load balancing, 1
for backup).
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
-----Original Message-----
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of deji@xxxxxxxxxxxxxx
Sent: Sunday, December 11, 2005 12:31 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
>>> RFC 2821 requires a mail server to choose MX records randomly when
>>> the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Correct. There was, however, an issue early this year (or was it late last
year?) where 2K3 SMTP servers were failing to fail over to the next
available SMTP servers on the list they receive from a target DNS server. I
think this was corrected with a hotfix, but the issue will still exist in a
gold, un-hotfixed version.
>>>The above means it will try MX of other priorities right (not the
>>>other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
It will continue to use the highest one, until that one stops responding. As
long as the highest-prioritized one continues to accept emails, the
originating server will have no need to try another one.
HTH
Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCT
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about
Yesterday? -anon
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of Freddy HARTONO
Sent: Sat 12/10/2005 7:07 AM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi Michael
Thanks for the quick reply.
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
The above means it will try MX of other priorities right (not the other of
the same priorities correct?) - sorry just not having a clear word by word
answer in the RFC document itself.
One of my vendor is giving me a whitepaper from barracuda appliance that
explains how its done, but mentioned that with MX listing below it will
provides load balancing AND redundancy (crap to me but now im getting
confused myself)
http://www.barracudanetworks.com/ns/downloads/Barracuda_WP_MX_Load_Balancing
.
pdf
Is it recommended that the TTL for the domain be set to 0 when using this MX
load balancing method?
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Michael B. Smith
Sent: Friday, December 09, 2005 8:52 PM
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: RE: [ActiveDir] [Way OT] DNS MX load balancing questions...
You should have two separate MX records
@ IN MX 10 mail1.mydomain.com.
@ IN MX 10 mail2.mydomain.com.
Mail1 IN A 10.1.1.1
Mail2 IN A 10.2.2.2
RFC 2821 requires a mail server to choose MX records randomly when the
records are the same priority, but to try all if the initial one chosen
doesn't work (until it finds one that does work or the pool is exhausted).
Your proposal below has the problem you describe.
________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx
[mailto:ActiveDir-owner@xxxxxxxxxxxxxxxxxx] On Behalf Of Freddy HARTONO
Sent: Friday, December 09, 2005 7:43 AM
To: activedir@xxxxxxxxxxxxxxxxxx
Subject: [ActiveDir] [Way OT] DNS MX load balancing questions...
Hi All
Was just trying to understand something and am getting conflicting results..
If I set the following (or 2 mx of the same priority with 2 differnet a
records)
Mydomain.com MX 10 mail.mydomain.com
Mail.mydomain.com A 10.1.1.1
Mail.mydomain.com A 10.2.2.2
I understand that will provide dns roundrobin but what happened if I
shutdown 10.2.2.2, will I lose (logically) 50% of my mail as I do not have
another fallback MX??
My understanding is that it does so as the sender mail server will cache the
MX record and A record and will only send to there, am I right or am I
getting this wrong?
If I'm shutting down 10.2.2.2, will the sender mail server retries to
10.1.1.1? (lets assume there's no ttl reconfig to zero)
Thanks lots
Thank you and have a splendid day!
Kind Regards,
Freddy Hartono
Group Support Engineer
InternationalSOS Pte Ltd
mail: freddy.hartono@xxxxxxxxxxxxxxxxxxxx
phone: (+65) 6330-9785
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
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List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ | | | |
| SteveRochford
Posts:10
| | 12/15/2005 7:37 AM |
| ________________________________
From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of AdamT
Sent: Mon 12/12/2005 18:13
To: ActiveDir@xxxxxxxxxxxxxxxxxx
Subject: Re: [ActiveDir] [Way OT] DNS MX load balancing questions...
On 12/11/05, Freddy HARTONO wrote:
>
> That means it makes no sense to invest in having 1 backup MX of lower
> priorities?
>
It makes perfect sense to have a backup MX of a lower priority. Most
of your users may be located in New York, so you'd want most of your
mail routed in that way, and would only want the mail server at your
remote site in London to accept mail if NYC was down for some reason.
Your London server might be sitting on a very slow connection to the
outside world, or maybe it's a fairly old machine and not up to
handling high loads, meaning you'd probably only want it to be used in
an emergency.
--
AdamT
"Maidenhead is *not* in Kent"
List info : http://www.activedir.org/List.aspx
List FAQ : http://www.activedir.org/ListFAQ.aspx
List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
> | | | |
| amulnick
Posts:127
| | 12/15/2005 8:35 AM |
| That right there is enough of a reason to not run secondary weighted
MX records. There would be no point if you actually had increased
traffic to that MX. In theory, if you increased the anti-spam
measures to be equal, what would be the point of having lower MX
records other than to put valid mail to an MX on the site with the
biggest amount of users (and therefore most likely although not
certainly going to get the most email volume?)
With today's spammers and other phraudsters prowling looking for
weaknesses, it takes away the need for a lower weighted mx in most
cases. Using a backup mail delivery system service might be a reason
to use lower weighted, but I can't think of any scenarios where I host
my own where I'd put out anything other than equally available,
powerful and connected systems. It no longer makes a lot of sense to
me in today's environments since I can't predict where the load would
be sent at a given point in time.
My $0.04 anyway.
Al
On 12/15/05, Steve Rochford wrote:
> Beware of the fact that many spammers now target low priority MX records on the assumption that they will be "backup" devices and perhaps doing less spam checking.
>
> Over the past 7 days, an average of 61% of all mail delivered to our secondary MX has been Spam compared to 39% of that to the 1y MX (and I suspect that the actual percentage of spam is higher - it's just not being picked up!)
>
> On the basis that nothing should be delivering to the 2y MX while the 1y is available, I've made sure that it's running ever fiercer spam catching rules in a bid to keep out the dross!
>
> Steve
>
> ________________________________
>
> From: ActiveDir-owner@xxxxxxxxxxxxxxxxxx on behalf of AdamT
> Sent: Mon 12/12/2005 18:13
> To: ActiveDir@xxxxxxxxxxxxxxxxxx
> Subject: Re: [ActiveDir] [Way OT] DNS MX load balancing questions...
>
>
>
> On 12/11/05, Freddy HARTONO wrote:
> >
> > That means it makes no sense to invest in having 1 backup MX of lower
> > priorities?
> >
> It makes perfect sense to have a backup MX of a lower priority. Most
> of your users may be located in New York, so you'd want most of your
> mail routed in that way, and would only want the mail server at your
> remote site in London to accept mail if NYC was down for some reason.
> Your London server might be sitting on a very slow connection to the
> outside world, or maybe it's a fairly old machine and not up to
> handling high loads, meaning you'd probably only want it to be used in
> an emergency.
>
> --
> AdamT
> "Maidenhead is *not* in Kent"
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