SUMMARY: udp_ttl Value is way too small .........

From: Thomas Leitner <tom_at_radar.tu-graz.ac.at>
Date: Mon, 12 Mar 2001 13:20:28 +0100 (MET)

Hi,

This is a summary without a question to save you all some time:

I was experiencing severe DNS problems today. Some domain names just
could not be resolved -- but only when they were queried from Tru64
machines (any version up to 5.1). Other machines like Solaris, Linux
and Windows NT could resolve these domain names just fine.

It took me 2 hours including packet sniffs on our firewall to figure
out the reason: The default TTL (time to live) value for UDP Packets is
way too small under Tru64. It defaults to 30 which is not enough for
the number of hops required to reach certain sites. This lead to the
situation that some adresses just could not be resolved when one of
the DNS servers was more than 30 hops away!

To fix it, use this command:

  # sysconfig -r inet udp_ttl=250

To make the fix permanent, add this to /etc/sysconfigtab

inet:
        udp_ttl=250

Maybe the next Tru64 version comes with a higher default TTL for UDP.

Tom

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Received on Mon Mar 12 2001 - 12:21:46 NZDT