Bind sometimes SERVFAIL

Pawel Rutkowski rutekp at freelance-worker.net
Wed Nov 11 06:42:14 UTC 2009


Hello,

    My Internet ISP give two nameservers address.
But when I'm asking those two servers sometimes I get:
[root at linux ~]# host d.yimg.com ns.my.isp
Using domain server:
Name: ns.my.isp
Address: ns.my.isp#53
Aliases:
Host d.yimg.com not found: 2(SERVFAIL)

but sometimes I get:

[root at linux ~]# host d.yimg.com ns.my.isp
Using domain server:
Name: ns.my.isp
Address: ns.my.isp#53
Aliases:
d.yimg.com is an alias for geoycs-d.gy1.b.yahoodns.net.
geoycs-d.gy1.b.yahoodns.net is an alias for fo-anyycs-d.ay1.b.yahoodns.net.
fo-anyycs-d.ay1.b.yahoodns.net has address 98.137.80.54


He explain me this thats a normal because of this:
http://www.faqs.org/rfcs/rfc2308.html
Some resolvers incorrectly continue processing if the authoritative
   answer flag is not set, looping until the query retry threshold is
   exceeded and then returning SERVFAIL.  This is a problem when your
   nameserver is listed as a FORWARDER for such resolvers.  If the
   nameserver is used as a FORWARDER by such resolver, the authority
   flag will have to be forced on for NXDOMAIN responses to these
   resolvers.  In practice this causes no problems even if turned on
   always, and has been the default behaviour in BIND from 4.9.3
   onwards.

Is this true ?

Thanks
Pawel R.






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