You will probably find that the host is actually in a different domain; for example, if you are in foo.example.org and you wish to reach a host called mumble in the example.org domain, you will have to refer to it by the fully-qualified domain name, mumble.example.org, instead of just mumble.
Traditionally, this was allowed by BSD BIND resolvers. However the current version of bind (see named(8)) that ships with FreeBSD no longer provides default abbreviations for non-fully qualified domain names other than the domain you are in. So an unqualified host mumble must either be found as mumble.foo.example.org, or it will be searched for in the root domain.
This is different from the previous behavior, where the search continued across mumble.example.org, and mumble.edu. Have a look at RFC 1535 for why this was considered bad practice, or even a security hole.
As a good workaround, you can place the line
search foo.example.org example.org
instead of the previous
into your /etc/resolv.conf file (see resolv.conf(5)). However, make sure that the search order does not go beyond the ``boundary between local and public administration'', as RFC 1535 calls it.