What is a third level domain name?
Any domain name consists of at least two levels – a top level domain and the second-level domain. A domain name like ‘microsoft.com’ I a second level domain, which includes the domain name ‘microsoft’ and the top-level domain ‘.com’.
In order to distinguish your second-level domain name, you can even use a third level domain name, like “owa.intermedia.net.” In general a third level domain name is used to refer to different servers within different departments of a company. In this case, owa.intermedia.net refers to Outlook Web Access for Exchange customers of intermedia.net.