DNS lookup utility.

# To lookup the IP(s) associated with a hostname (A records):
dig +short hostname.com

# To lookup the mail server associated with a given domain name (MX record):
dig +short hostname.com MX

# To specify an alternate DNS server to query (8.8.8.8 is google's public DNS):
dig @8.8.8.8 hostname.com

# To perform a reverse DNS lookup on an IP address (PTR record):
dig -x 8.8.8.8

# To find authoritative name servers for the zone and display SOA records:
dig +nssearch hostname.com