DNS stops responding during bulk email send

[Mike Donnelly]

Using Small Business Server 2000, we have an ASP Web
application that we use to send periodic email
notifications to our customers using CDO. The ASP queries
our SQL customer database for the current email addresses
(about 4,000 are returned), then sends each recipient a
separate email. Within a few minutes, the DNS stops
responding to domain name requests, and all email queues
go to "Retry" state. Eventually the emails are "delayed",
then returned with a DNS error. The problem is
temporarily fixed by bouncing the DNS Server process, but
it stops working again within 2 minutes. This only seems
to happen when we send the bulk email, and not during our
normal daily traffic.

 

[Kevin D. Goodknecht [MVP]]

In

Using Small Business Server 2000, we have an ASP Web
application that we use to send periodic email
notifications to our customers using CDO. The ASP queries
our SQL customer database for the current email addresses
(about 4,000 are returned), then sends each recipient a
separate email. Within a few minutes, the DNS stops
responding to domain name requests, and all email queues
go to "Retry" state. Eventually the emails are "delayed",
then returned with a DNS error. The problem is
temporarily fixed by bouncing the DNS Server process, but
it stops working again within 2 minutes. This only seems
to happen when we send the bulk email, and not during our
normal daily traffic.

Is port 53 TCP open through your firewall and to the DNS server?

 

[Ace Fekay [MVP]]

This may require an SP update. May also suggest to check with the SBS
groups.

--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS IS" with no warranties.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory

 

[William Stacey]

Hmm. Like Ace said, I would first apply any SPs to eliminate the fact that
this is a bug that was fixed. If you still have issues after that, I would
be interested in seeing another post on this so we can dig a bit deeper.
Cheers!

 

[Mike Donnelly]

ISA seems OK - I just applied a Microsoft patch that I
found last week. The first 100 or so go out fine, then
the DNS stops resolving addresses. Each time I bounce the
DNS service, it starts up normal again for a few hundred,
then stops responding again.

 

[William Stacey]

hmm. Well we have to make a diag decision here. What approach will give us
the best bang for our buck?
1) We could start down the NetMon path and look at dns packets to see what
is happening.
2) We could see if this may be a SBS DNS issue or a W2K DNS issue (not sure
if implementation is 100% same.)
3) We could do some dig.exe testing before and after failure combined with
#1 above.

I think I would probably go with #2 first if you can setup a w2k or w3k box
for testing. Setup as a server (no AD) and add a zone and add your
forwarders to it and get it running and replying to queries. Then point
your email server to it and let-r-rip. If you have same issue, that would
be very interesting and require #1 and #3 above. If you don't, then its
probably a SBS issue, and we could start drilling down on that.

 

[Ace Fekay [MVP]]

Have you run an AV scan? Starting to think a virus issue (poosibly), such as
the QHost virus.

Are any of your other services turned off or disabled? I'm assuming this is
a firewall client of ISA? Yes, ISA can be a client of itself. Can you bypass
ISA completely to see if it works?

Have you tried to post this to SBS yet? The reason I ask, it could be SBS
related, like many other things are in tech supporting SBS. If so, what sort
of suggestions did they offer?


--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS IS" with no warranties.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory

 

[William Stacey]

Good point Ace, I did not think to check for virus first. This would always
be good before going down a long diag path. Cheers!

 

[Kevin D. Goodknecht [MVP]]

In

ISA seems OK - I just applied a Microsoft patch that I
found last week. The first 100 or so go out fine, then
the DNS stops resolving addresses. Each time I bounce the
DNS service, it starts up normal again for a few hundred,
then stops responding again.

Have you enabled a forwarder for your DNS server?
You could also try to enable a forwarder or two then check the box on the
forwarders tab "Do not use recursion" This will pass all external queries to
the forwarders and prevent your DNS server from resolving the queries itself
by using root hints.
This is NOT the same as "Disable recursion" on the advanced tab, it simply
forces DNS to use its forwarders for recursive queries. It takes a lot less
CPU for DNS when set up this way, because it will not have to do its
recursive lookups itself, it basically converts your DNS server to a caching
proxy DNS but still allows it to answer authoritatively for its local zones.

 

[Ace Fekay [MVP]]

Thanks. It was more of a guess at this point, but yes, if it is the prob,
it would eliminate a long unnecessary diag path...
Cheers!

Ace

 

[Ace Fekay [MVP]]

In

In

Have you enabled a forwarder for your DNS server?
You could also try to enable a forwarder or two then check the box on
the forwarders tab "Do not use recursion" This will pass all external
queries to the forwarders and prevent your DNS server from resolving
the queries itself by using root hints.
This is NOT the same as "Disable recursion" on the advanced tab, it
simply forces DNS to use its forwarders for recursive queries. It
takes a lot less CPU for DNS when set up this way, because it will
not have to do its recursive lookups itself, it basically converts
your DNS server to a caching proxy DNS but still allows it to answer
authoritatively for its local zones.

--
Best regards,
Kevin D4 Dad Goodknecht Sr. [MVP]
Hope This Helps
============================

Hmm, excellent suggestion. Curious to see if this helps out.

--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS IS" with no warranties.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory