Which protocol below uses TCP port 443?（）

多项选择题Regarding DHCP (dynamic host configuration protocol), which two of the following choices below are true?（）

A. The DHCP Discover message uses FF-FF-FF-FF-FF as the Layer 2 destination address.
B. The DHCP Discover message uses UDP as the transport layer protocol.
C. The DHCP Discover message uses a special Layer 2 multicast address as the destination address.
D. The DHCP Discover message uses TCP as the transport layer protocol.
E. The DHCP Discover message does not use a Layer 2 destination address.
F. The DHCP Discover message does not require a transport layer protocol.

多项选择题A legacy network that is prone to errors may have issues with services that use UDP. Which of the following services could have problems in this case, due to the fact that UDP is used?（）

A.DNS
B.Telnet
C.SMTP
D.SNMP
E.HTTP
F.TFTP

单项选择题The corporate head office of TestKing has a teleconferencing system that uses VOIP (voice over IP) technology. This system uses UDP as the transport for the data transmissions. If these UDP datagrams arrive at their destination out of sequence,what will happen?（）

A. UDP will send an ICMP Information Request to the source host.
B. UDP will pass the information in the datagrams up to the next OSI layer in the order that they arrive.
C. UDP will drop the datagrams.
D. UDP will use the sequence numbers in the datagram headers to reassemble the data in the correct order.
E. UDP will not acknowledge the datagrams and wait for a retransmission of the datagrams.

多项选择题Although TCP segments differ from UDP segments, they both contain some common fields. What two segments do they share in common?（）

A. source address
B. options
C. sequence number
D. sources
E. destination port
F. checksum

多项选择题Which of the following protocols utilize TCP?（）

A. NTP
B. NNTP
C. SMTP
D. SNMP
E. HTTPS
F. TFTP