My resolv.conf looks like this:
; generated by /sbin/dhclient-script
search mcdc
nameserver 10.0.4.48
nameserver 8.8.8.8
if I do nslookup www.google.com
it works
nslookup www.google.com
;; Got SERVFAIL reply from 10.0.4.48, trying next server
Server: 8.8.8.8
Address: 8.8.8.8#53
Non-authoritative answer:
www.google.com canonical name = www.l.google.com.
but when I curl www.google.com, it cannot resolve the host.
I tried running curl under strace, and found curl was only using the first nameserver in resolv.conf, not the second. If I switch the two nameserver lines around, www.google.com resolves, but internal DNS names do not, so thats not a good workaround.
How can I fix resolv.conf to use both nameservers?
Best Answer
The default behavior for resolv.conf and the resolver is to try the servers in the order listed. The resolver will only try the next nameserver if the first nameserver times out. The resolv.conf manpage says:
And:
Also see the resolver(5) manual page for more information.
You can alter the resolver's behavior using
rotate
, which will query the Nameservers in a round-robin order:However, nslookup will use the second nameserver if it receives a
SERVFAIL
from the first nameserver. From the nslookup manpage: