On 5/26/2011 2:51 PM, Dan Pritts wrote:
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.
Dan,
I don't know the exact timing, but with BIND it's on the order
of tenths of a seconds (or 100s of milliseconds, if you prefer). 2
seconds would be way too slow.
It shouldn't be hard to set up a test delegation with one "dead"
nameserver and restart/query named a few times to see how long the
failover takes...
- Kevin
P.S. You guys are practically next door to where I live (Pitt Twp), let
me know if you need any help with this :-)
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