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DNS Resolution Issue / Email Issue

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3 replies

by sean mullin

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I am having an issue with Exchange Queues backing up. It appears to be that I can't resolve the remote mail server. If I restart my DNS server (on my local DC) the remote server resolves and mail goes on its way. About 2 hours later, the same issue. Seems that perhaps I have some DNS poisoning or cache issues. Any help on troubleshooting this would be appreciated.

3 replies

by amenhsys

1st A mailserver need to be able to resolve domain for MX records of recipient domain. IF my guess is right you are running your domain in this format domain.local. Do the following

1. The DNS on your network should eb configured to forward all non answered domian queriesto the DNS of your ISP or external DNS servers.

2. DC should be able/configured to resolve any external domain. Forward non local domain queries to your ISP's DNS servers. You can test this by doing a NS lookup c\:>NSLOOKUP

3. Ensure that all your servers (DNS) have unrestricted/allowed access to Ports udp/53

IF 1-3 IS IN ORDER YOU SHOULD HAVE NO PROBLEMS

by sean mullin

In this case it is only one domain. It looks like my dns cache is getting poisoned. But all my troubleshooting other than symptoms seems to rule this out.

As a work around I have a batch script that restarts dns every 3 hours and the problem doesn't crop up.

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