Several DNS lookup utilities provide name and IP address resolution from the command line. The host and nslookup commands are two commonly installed utilities.

The host command lists all of the IP addresses attached to a domain name:

$ host google.com 
google.com has address 64.233.181.105 
google.com has address 64.233.181.99 
google.com has address 64.233.181.147 
google.com has address 64.233.181.106 
google.com has address 64.233.181.103 
google.com has address 64.233.181.104 

The nslookup command maps names to IP addresses and will also map IP addresses to names:

$ nslookup google.com 
Server:    8.8.8.8 
Address:  8.8.8.8#53 
 
Non-authoritative answer: 
Name:  google.com 
Address: 64.233.181.105 
Name:  google.com 
Address: 64.233.181.99 
Name:  google.com 
Address: 64.233.181.147 
Name:  google.com 
Address: 64.233.181.106 
Name:  google.com 
Address: 64.233.181.103 
Name:  google.com 
Address: 64.233.181.104 
 
Server:    8.8.8.8 

The last line in the preceding command-line snippet corresponds to the default name server used for resolution.

It is possible to add a symbolic name to the IP address resolution by adding entries into the /etc/hosts file.

Entries in /etc/hosts follow this format:

IP_ADDRESS name1 name2 ... 

You can update /etc/hosts like this:

# echo IP_ADDRESS symbolic_name>> /etc/hosts 

Consider this example:

# echo 192.168.0.9 backupserver>> /etc/hosts 

After adding this entry, whenever resolution to backupserver occurs, it will resolve to 192.168.0.9.

If backupserver has multiple names, you can include them on the same line:

# echo 192.168.0.9 backupserver backupserver.example.com >> /etc/hosts