dig

Domain Information Groper
generates a DNS query
prints the response "as is"
Basic command line description
dig [@server_address] [RR_type] domain_name
server_address
/etc/resolv.conf will be used when unspecified
use numeric address to avoid confusion
RR_type
A RR by default
specify "AAAA" for looking up IPv6 addresses
Important output fields
"ANSWER SECTION"
"status" and "flag" in HEADER