The /etc/resolv.conf
file configures how the Linux system resolves hostnames. It contains the resolvers that the system will query in order to convert hostnames to IP addresses and vice versa.
In addition to listing resolving servers the resolv.conf
file can also take the search
option that will save you a great deal of typing in the right situation.
The search
option takes a list of space-separated hostnames. Here is an example of the search option being used for two domain names:
search example.com example.org
These hostnames will be appended to any hostname which does not itself resolve and the new hostname checked to see if it resolves.
This is incredibly useful because many organizations tend to give their servers subdomains a small number of domain names e.g.:
web1.example.com
web2.example.com
filestore.example.com
db.example.com
In this situation, putting this line into /etc/resolv.conf
:
search example.com
Means you no longer have to use:
ssh root@web1.example.com
to SSH into web1.example.com
but instead can simply type:
ssh root@web1
and example.com
will be automatically appended to web1
. This will work for any command that uses hostnames on the command line and save you a lot of typing.