nanog mailing list archives

Re: Do I or RR need dns clue?


From: "Tuc at T-B-O-H.NET" <ml () t-b-o-h net>
Date: Thu, 16 Aug 2007 14:16:01 -0400 (EDT)


On Thu, 16 Aug 2007 10:40:49 EDT, Tuc at T-B-O-H said:

Mail to RR users is getting refused due to PTR issues. I contacted
RR and explained that yea, one of our 2 DNS servers for the
IN-ADDR.ARPA is down, but the other is fine.  They said that 
I should either get the DNS server back up (Which of course
is already being worked on, was the minute it went down)
or delete it from ARIN IN-ADDR.ARPA records.

Isn't the whole point of multiple DNS servers that if one is down
the other can still answer queries? Or am I missing something
here???

Depends exactly what your "down" server is doing.  If it's totally not
answering, the resolver at RR should silently fall back and try the other one.

It gets more interesting if your "down" server is still answering queries,
particlylarly if it's giving out "I never heard of it" answers with the
authoritative bit set because it's blown out a zone.  In that case, the RR
resolver is within its rights to assume that your NS knows what it's talking
about and believing it.

Hi,

        Down is there isn't power to it until it gets repaired. So its not
answering period. A "nslookup" shows "timed-out". A "dig" shows 
"connection timed out; no servers could be reached" (When querying ONLY
against the down server).

        So how do I go back to RR, who told me to take it out of my 
NS records, that DNS is supposed to be silently falling back and trying
again? 

                        Thanks, Tuc/TBOH


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