A.source ip address：192.168.15.5destination port：21
B.source ip address：，192.168.15.37destination port：21
C.sourcei p address：，192.168.15.41destination port：21
D.source ip address：，192.168.15.36destination port：23
E.source ip address：192.168.15.46destination port：23
F.source ip address：，192.168.15.49destination port：23

A.They are always present in the NAT table.
B.They allow connection to be initiated from the outside.
C.They can be configured with access lists,to allow two or more connections to be initiated from the outside.
D.They require no inside or outside interface markings because addresses are statically defined.