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We have a Windows 2008 SP2 DNS server configured to use root hints. We have a certain MX record lookup that it periodically fails to resolve for our client machines.

The lookup is for the MX record for, which should resolve to

Periodically our DNS server returns SERVFAIL error indicating it cant resolve the A record for

From my research, it appears to be related to the different TTL values of the MX record, and the A record. The MX record has a TTL of 3600, the A record has a TTL of 60.

Has anyone experienced this issue before? Where the A record expires before the CNAME does, and causes your DNS server to return SERVFAIL error when attempting to resolve a MX record? Various technet articles recommend either enabling DNS forwarders, or decreasing your MaxCacheTTL entry. I simply dont understand why these would correct the issue? Why would the DNS server not just use root hints to lookup the A record again?

LINK: Technet article describing similar issue

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