For example, resolv.conf in /etc/ looks like this:-
search example.com
nameserver 172.16.1.254
nameserver 172.16.2.254
options timeout:3
options attempts:2
Here, timeout 3 means 3 seconds. But, what is the significance for timeout value? Is it the time taken to connect to DNS server? OR Is it the time allowed to wait for DNS server to return IP address value for a URL?
Yes exactly. Timeout value is time to resolving IP address from hostname through DNS. server,timeout option is to reduce hostname lookup time
timeout:n
sets the amount of time the resolver will wait for a
response from a remote name server before retrying the
query via a different name server. Measured in
seconds, the default is RES_TIMEOUT (currently 5, see
<resolv.h>). The value for this option is silently
capped to 30.
Refer http://man7.org/linux/man-pages/man5/resolver.5.html for more information