DNS Domain Search Order

When a query is made for a hostname that does not end with a dot, the hostname is extended to a fully qualified domain name before the query is passed to the name server. The domain name appended to the host name depends on what is entered in the Domain Suffix Search Order subwindow:

If nothing is entered, the hostname is extended with the default domain from the Domain box. For example, if the box contains plant.nuts.com and the hostname to be resolved is almond, the system creates a query for almond.plant.nuts.com. If this name cannot be resolved, the system checks the parent domain by generating a query for almond.nuts.com. That is as far as the search goes. The system will not append a parent domain name that contains less than two fields; it will not generate a query for almond.com because the top-level domains do not contain host addresses, only pointers to the servers for second-level domains.
If the subwindow contains the domain entries plant.nuts.com and sales.nuts.com, a request for the IP address of acorn generates a query for acorn.plant.nuts.com and then one for acorn.sales.nuts.com (assuming the first query was not successful). The system does not, however, search the parent domain nuts.com. Even the domain provided in the Domain box is not searched if there are entries in the Domain Suffix Search Order subwindow. When a search list is provided, it must include all of the default domains that you want searched.

A query is also issued for the name exactly as it is typed in by the user. If the user asks for the address of peanut.nuts.com, a query for that domain name is sent regardless of what is entered in the Domain Suffix Search Order subwindow. The default domains are only used to extend hostnames so that it is possible for a user to enter the names in a shorter form. Default domains do not interfere with the normal processing of a query.