DNS lookup server list and DNS search domain list

DNS lookup server list contains the DNS servers you want to send your DNS queries to.

DNS Search domain list contains the names of the domains that will be searched if you do not provide a fully-qualified domain name when trying to access a resource. For example, you want to ping host server1.example.com, and you have "example.com" in the search domain list, you can do just "ping server1" rather than "ping server1.example.com". Beware, though, of the risks of getting to the wrong server if you put in multiple subdomains in the list and there is a server called "server1" in all these subdomains.