The DNS suffix is the suffix that is appended to each virtual portal’s name, in order to create the virtual portal’s DNS name. For example, if a virtual portal’s name is myportal, and the DNS suffix is example.com, then the virtual portal’s DNS name will be myportal.example.com.
Your primary DNS suffix is what your computer has been told by some technology like DHCP, Group Policy, Network setup, or joining an Active Directory domain which DNS namespace it belongs to.
A connection specific DNS suffix is a DNS suffix that is related to a particular network interface. It can be used in addition to or instead of the Primary DNS suffix when performing DNS queries or DNS dynamic registrations.