dig – Domain Information Groper is a light weight Linux utility for querying DNS records. It is widely used to diagnose DNS servers, troubleshoot DNS servers, purge DNS Cache using external DNS server and dozen of great features it provides.
Here i am sharing quick cheat sheet of dig – DNS Lookup utility that every System/Network administrator should have print out at their desk.
In our examples, 8.8.8.8 is a Google Public DNS Server that can be use in /etc/resolv.conf
Why to use Google Public DNS ?
If you have a DNS record with high ttl e.g 3600 seconds, your local DNS server may not purge the old record from the cache. So better you use Google public DNS server to resolve it most recent update record.