DNS: Domino attempts to use an A record sending mail to certain domains

Technote (troubleshooting)


Problem

Using certain DNS servers, Domino will attempt to use an A record when sending mail to certain internet domains.

Under certain circumstances, after the problem described above is encountered, Domino will cache the A record. The cached A record will then be used for subsequent attempts to route mail to the same domain rather than a new DNS query being made. This can result in delivery failures after a 24 hour period.

Resolving the problem

These two issues have been reported to Quality Engineering as SPR# BSTS838NYV and SPR# JFBM7C6GA4.


1. SPR# BSTS838NYV: With two DNS servers configured and the primary unavailable, there are five requests for an MX record made to the primary DNS server. Then there is a new request made against the secondary DNS server, but for an A record rather than an MX record. See Technote #1423917 for additional information. This SPR is fixed in Notes and Domino 8.5.1 FP4 and 8.5.2.

2. SPR# JFBM7C6GA4: When an A record is used, Domino will sometimes cache the A record for 34 years. This can be seen by enabling debugrouter=3 on your server. Once enabled, you will be able see a timeout value on the console 34 years in the future. Development has discovered that Domino can incorrectly set a TTL (TimeToLive) of 34 years when DNS returns an NXDOMAIN (non-existent domain) record. This SPR is fixed in Notes and Domino 7.0.4 FP1 and 8.0.2 FP2.

Refer to the Upgrade Central site for details on upgrading Notes/Domino.

If you have not yet upgraded, as a workaround, use a Program document to issue the parameter "tell router update config" periodically. This will flush the DNS cache and result in another DNS query for the domain.



Document information


More support for:

IBM Domino
Mail Server

Software version:

7.0, 8.0, 8.5

Operating system(s):

Windows

Reference #:

1386420

Modified date:

2009-08-17

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