A.FTP B.Telnet C.SMTP D.DNS E.HTTP F.POP3
A.192.168.20.29 B.192.168.20.16 C.192.168.20.17 D.192.168.20.31 E.192.168.20.0
A.255.255.255.0 B.255.255.255.128 C.255.255.252.0 D.255.255.255.224 E.255.255.255.192 F.255.255.248.0