The corporate head office of Ezonexam 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

A.UDP provides delivery notification and error checking mechanisms.

B.UDP is faster than the Transmission Control Protocol (TCP).

C.UDP application examples include DNS and VoIP.

D.UDP is an application layer protocol.

E.UDP uses a best effort delivery approach.

A. UDP is faster than TCP

B. UDP operates at the Transport Layer

C. UDP is connection-oriented

D. UDP data is sent best-effort

E. UDP is more reliable than TCP

Network managers have long awaited practical voice-over-IP(VOIP)solutions. VOIP promises(71)network management and decreases costs by(72)a company's telephony and data infrastructures into one network. And a VOIP solution implemented at a company' s head -quarters with far -reaching branch offices can(73)tremendous amounts of(74)in long distance phone bills, provided that solution delivers POTS -like voice(75)over the Internet.

A．complicated

B．useful

C．ease

D．orderly

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.

【A popular service that has attercted the interest of companies and has home users alike is the sending of voice signals over an IP-based network, such as the Internet. The practice of making telephone calls over the internet has had a number of different names, including packet voice, voice over packet, voice over the internet, internet telephone, and Voice over Ip（Voip）. But it appears the industry has settled on the term”Voice ove IP” in reference to the internet protocol, which controls the transfer of data over the internet. There are currently three ways to deliver VoIp to users, the first technique is found at the corporate level. Many companies are offering VoIP systerms that operate over a local area network. These systems involve a fair amount of equipment, such as VoIP servers, special IP-enabled telephones, and routers that can direct telephone calls. Today a large portion of corporate sites have converted their older internal telephone systems to VoIP systems that opreate over a LAN, thus converging two systems into one. A second common solution is the one often encountered at home. Using existing telephones, a special converter is added between the telephone and a high speed internet（DSL or cable modem）connection. The converter digitizes the voice signal and creates a stream of packets that are then sent over an ip connection.The third technique involves smart cell phones. Never cell technologies are all packet-based, thus requiring a telephone call to be converted to digital packets and sending those packets over IP networks.】

From the paragraph above，a popular service that has attracetd the interest of companies and home users,is termed as （） . The data transfer over the Internet is controlled by the （） . At corporate level, many companies have replaced their older internal telephone systerms with （） that oprerate over a local area network.

A、voice over the internet B、voice over packet C、Voice over IP D、internet telephony A、packet B、internet protocol C、industry D、VoIp servers A、VoIP systems B、IP-enablde telephones C、VoIP servers D、routers

A. SONET and SDH both use time-division multiplexing.

B. An optical transport network system uses time-division multiplexing.

C. SONET and SDH both use wavelength-division multiplexing.

D. An optical transport network system uses wavelength-division multiplexing.

Network managers have long awaited practical voice-over-IP(VOIP)solutions. VOIP promises ease network management and decreases(66)by converging a company's telephony and data infrastructures into one network. And a VOIP solution implemented at a company's head-quarters with far-reaching branch offices can(67)tremendous amounts of money in long distance phone bills, provided that solution delivers POTS-like voice(68)over the Internet.

VOIP gateways are designed to convert voice from the(69)domain to the circuit switched domain. VOIP solutions use a digital signal processor(DSP)to process the voice data, preparing the voice sample for transmission by compressing voice and removing jitter. The VOIP equipment must comply with the(70)H.323 standard defined by the International Telecommunication Union, or ITU.

A．time

B．cash

C．costs

D．space

During the boot sequence, a Ezonexam 2800 series router needs to locate and load an operating system. What is the default order the router uses to find an operating system?

A．ROM, TFTP server, Flash

B．Flash, TFTP server, ROM

C．Flash, NVRAM, TFTP server

D．Flash, ROM, TFTP server

E．Flash, TFTP server, RAM

● Each machine supporting TCP has a TCP transport entity, either a library procedure, a user process, or part of the kernel. In all case, it manages TCP streams and （71） to the IP layer. A TCP （72） accepts user data streams from local process, breaks them into pieces not exceeding 64KB, and sends each piece as a separate IP （73） . When datagrams containing TCP data arrive at a machine, they are given to the TCP entity, which reconstructs the original byte streams. The IP layer gives no guarantee that datagrams will be delivered properly, so it is up to TCP to time out and （74） them as need be. Datagrams do arrive may well do so in the wrong order, it is also up to TCP to （75） them into messages in the proper sequence.

（71）

A. calls

B. interfaces

C. links

D. produces

（72）

A. connection

B. file

C. entity

D. destination

（73）

A. datagram

B. stream

C. connection

D. transaction

（74）

A. reassemble

B. reduce

C. re-create

D. retransmit

（75）

A. reassemble

B. reduce

C. re-create

D. retransmit