nslookup command is used to verify DNS settings. To find A record of a domain, run

nslookup DOMAIN-NAME

Example

boby@hon-pc-01:~ $ nslookup www.flashwebhost.in
Server:		8.8.8.8
Address:	8.8.8.8#53

Non-authoritative answer:
www.flashwebhost.in	canonical name = ppy82.x.incapdns.net.
Name:	ppy82.x.incapdns.net
Address: 107.154.168.41

boby@hon-pc-01:~ $

Find MX Record of a Domain

nslookup -q=mx DOMAIN-NAME

Example

boby@hon-pc-01:~ $ nslookup -q=mx hostonnet.com
Server:     8.8.8.8
Address:    8.8.8.8#53

Non-authoritative answer:
hostonnet.com   mail exchanger = 10 aspmx3.googlemail.com.
hostonnet.com   mail exchanger = 5 alt1.aspmx.l.google.com.
hostonnet.com   mail exchanger = 10 aspmx2.googlemail.com.
hostonnet.com   mail exchanger = 10 aspmx5.googlemail.com.
hostonnet.com   mail exchanger = 1 aspmx.l.google.com.
hostonnet.com   mail exchanger = 10 aspmx4.googlemail.com.
hostonnet.com   mail exchanger = 5 alt2.aspmx.l.google.com.

Authoritative answers can be found from:

boby@hon-pc-01:~ $