DNS...urgent...!!

[pslum_ironport]

I have a problem now with a customer, every since one of the antivirus mail gateway which sit in between the mail server and ironport is down. This mail gateway responsible to relay mail from ironport to exchange or vice versa.
now, they have about 20k mail being queue for deliver. and i alway get a error : maximum number of concurrent DNS queries (500) reached, Every time i dnsflush and deliver i see this error. and the domain which is still try to send out from ironport are always down. please advice...!!!

[David Graham_ironport]

Is this mail coming in that is waiting in queue or mail that is going out? Either way, it sounds like the one server is still acting as the bottle neck and it is not being bypassed. If the server was not the sole DNS server I would see if you could bypass it for now. Possibly change the SMTP destinations under the Network tab to bypass.

ANother question would be if you could telnet to the mail host from the ironport CLI. If you have not done this before the command would be telnet mailhost.domain.com 25. You should see a greeting from the mail host. If you do not, then it is either a DNS issue (which ping or nslookup may help resolve) or the mail server that is receiving is down/not accepting emails.

Right now it is pretty wide open.

[kluu_ironport]

This knowledge base article may help,

Warning: Maximum number of concurrent DNS queries (500) reached

http://tinyurl.com/yyb2mv

It may be that you have a slow local dns server. Try switching to use the Internet root servers. If you switch to the root servers, do a "dnsflush" afterwards. The article gives some other recommendations too.

I have a problem now with a customer, every since one of the antivirus mail gateway which sit in between the mail server and ironport is down. This mail gateway responsible to relay mail from ironport to exchange or vice versa. 
        now, they have about 20k mail being queue for deliver. and i alway get a error : maximum number of concurrent DNS queries (500) reached, Every time i dnsflush and deliver i see this error. and the domain which is still try to send out from ironport are always down. please advice...!!!

[pslum_ironport]

if i used root DNS, the work queue will increase, i am not sure why this is happening ever since the mcafee antivirus mail gateway down.