1. [单选题]A receiving host has failed to receive all of the segments that it should acknowledge.What can the host do to improve the reliability of this communication session?
A. Start a new session using UDP
B. Obtain a new IP address from the DHCP server
C. Use a different source port for the session
D. Decrease the sequence number
E. Decrease the window size
2. [单选题]帧中继环境中，在物理端口上，建立子接口的命令是（）
A. create
B. interface
C. encapsulation
D. ip address
