dig command to test your DNS
Returns any A record found within the queried hostname's zone.
dig [hostname] [record type]
Returns the records of that type found within the queried hostname's zone.
dig [hostname] +short
Provides a brief answer, usually just an IP address.
dig @[nameserver address] [hostname]
Queries the nameserver directly instead of your ISP's resolver.
dig [hostname] +trace
Adding +trace instructs dig to resolve the query from the root name server downwards and to report the results from each query step.
dig -X [IP address]
Reverse lookup for IP addresses.
dig [hostname] any
Returns all records for a hostname.