DNS

Trace DNS Route
dig +trace domain.name

Global DNS Propagation Checker - What's My DNS?
http://www.whatsmydns.net is an online service that allows you to instantly perform a DNS lookup to check a hostnames current IP Address and other DNS information against a selection of random name servers around the world. This is especially useful to check the current state of DNS propagation after making changes to your domains zones.

All Good DNS Servers In One
Edit your /etc/network/interfaces file and add this line...

dns-nameservers 208.67.222.222 208.67.222.220 8.8.8.8 8.8.4.4

e.g.

auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 192.168.0.2 netmask 255.255.255.0 network 192.168.0.0 broadcast 192.168.0.255 dns-nameservers 208.67.222.222 208.67.222.220 8.8.8.8 8.8.4.4 gateway 192.168.0.1

OpenDNS Public DNS Servers
nameserver 208.67.222.222 nameserver 208.67.220.220

Google Public DNS Servers
nameserver 8.8.8.8 nameserver 8.8.4.4

Plus Net DNS Servers
nameserver 212.159.6.9 nameserver 212.159.6.10

Dig
dig @nameserver hostname type

e.g.

dig @8.8.8.8 indie-it.com A

DNS Look Up
Linux Terminal $: host www.indie-it.com

Windows Command Prompt $: nslookup www.indie-it.com