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?（）

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

单项选择题Which one of the following protocols uses both UDP and TCP ports for the transport layer operation?（）

A.FTP
B.TFTP
C.SMTP
D.Telnet
E.DNS

多项选择题Which of the following protocols utilize UDP as the layer 4 transport mechanism?（）

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