recursive server querying authoritative - timeout before trying next server?

Dan Pritts danno at internet2.edu
Thu May 26 18:51:12 UTC 2011


Hi,

A question regarding BIND defaults.  I'd love the same answer for other nameserver software if anyone
cares to share.

I am a recursive nameserver.  I am looking for foo.bar.com.  i've learned from bar.com that foo.bar.com has
four NS records.  I've never tried to talk to these servers before.  

I send a query to the address listed in the first NS record.  I never get an answer?

How long do I wait before trying the next one?

I looked through several RFCs but couldn't find anything specific in the spec.  RFC1035 mentions
that choosing this timeout would be up to nameserver implementors and suggests 5-10 seconds as
a reasonable default.  

my google-fu is failing me on this one.  I found something at Microsoft that suggests that their DNS server 
waits 3 seconds although i may have interpreted that wrong.  I found a reference to a nameserver  called 
"deadwood" that defaults to 2 seconds.  But, I couldn't find anything on BIND.  

thanks,
danno
--
Dan Pritts, Sr. Systems Engineer
Internet2
office: +1-734-352-4953 | mobile: +1-734-834-7224




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