NSLOOKUP will return the IP Address of a domain name by querying a computers assigned DNS Servers for the information. NSLOOKUP is well known as a Windows command but can be used on some Unix based systems as well.
Wikipedia
nslookup is a network administration command-line tool available in many computer operating systems for querying the Domain Name System (DNS) to obtain domain name or IP address mapping, or other DNS records The name "nslookup" means "name server lookup"