Difference between host, hostssl and hostnossl connection type

I would like to know what is the difference between host, hostssl and hostnossl connection type.

According to documentation,

host => This record matches connection attempts made using TCP/IP. host records match SSL or non-SSL connection attempts as well as GSSAPI encrypted or non-GSSAPI encrypted connection

attempts.

hostssl => This record matches connection attempts made using TCP/IP, but only when the connection is made with SSL encryption.

hostnossl => This record type has the opposite behavior of hostssl; it only matches connection attempts made over TCP/IP that do not use SSL.

I provided cert authentication method for host type connection. but i get error and postgres does not come up. Following is the error message i get.

LOG: cert authentication is only supported on hostssl connections.

Thanks,

Dhirendra.