NWC202

audio/video refers to the broadcasting of radio and TV programs through the Internet, [A] Interactive [B] Streaming stored [C] none is correct D. Streaming live

d

A TGP machine is sending full windows of 65,535 bytes over a 1-Gbps channel that has a 4-msec one-way delay, What is the line efficiency? [A] 2,6% IB] 13,1% C 0,3% D 6,5%

a

A set of rules which is used by computers to communicate with each other across a network is called [A] Network protocols [B] Network policies [C] Network archiectures D Network conventions

a

Assume that Seoul National University is assigned with IP addresses written as 194,6,96,0/30, what is the first address and the lass address of the university [A] 194,6,96.0 and 194.6,06,255 [B] 194,6,96.250 and 194,6,96,255 [C] 194.6.96.0 and 194.6,96,3 D 194.6.96.1 and 194.6,96255

a

DNS can use the services of using the well-known port 53, [A] either (UDP) or (TCP) [B] TCP [C] none of them D UDP

a

Many coding systems include an extra bit called a , for error detection purposes, [A] parity bit [B] checking bit [C] control bit D padding

a

Parity checking, [A] can detect a single bit error in a transmission [B] can detect an even number of bit errors [C] adds an odd bit even if no errors occurred, for safety D is not used if the circuits are at parity

a

The purpose of MTA (Mail Transfer Agent) is. [A] Transferal of message across the Internet [B] Envelope creation [C] Message preparation D (Message preparation} and (Envelope creation)

a

What does NAT stand for? [A] Network Address Translation [B] Network Address Table [C] Network Address Transfer D Network Address Taking

a

Which ones are correct for Repeaters? [A] To increase the transmission distance [B] Work at physical layer [C] All of them D To amply the transmitted sig

a

Which protocol is better for real-time video application overthe Internet in term of minimizing the delay? A. UDP B. TCP C. ARP D. ICMP

a

With WWW as an example of client-server computer software, the server is: [A] The machine that makes WWW documents available, [B] The machine that enables you to connect to the internet, [C] The machine that you use to display WWW documents, D All are correct

a

In CRC, if the generator is x A4+x+1, then which one is added into the frame before dividing [A] 11111 [B] 0000 [C] 1111 [D] 00000

b

In Congestion avoidance of TCP congestion control, when timeout occurs, the congestion window. [A] Reduces by half [B] Reduces to 1 [C] Remains the same D None is correct

b

In error reporting the encapsulated ICMP packet goes to [A] None of them [B] the original sender [C] the receiver D a route

b

In the DNS, the names are defined in structure [A] a linear list [B] an inverted-tree [C] none is correct [D] a grap

b

In the osi model, which of the following is an application layer service? [A] mail service [B] all are correct [C] file transfer, access, and management D network virtual terminal

b

Jitter is introduced in real-time data by the, [A] both (error caused during transmission) and (Difference of the delay among packets) [B] Difference of the delay among packets [C] none is correct D error caused during transmission

b

Network layer does not provide reliable transmission because [A] none is correct [B] There is no acknowledgment process in the network layer [C] It uses acknowledgement for every transmitted packet D It does not use the sequence number

b

TCP assigns a sequence numberto each segment that is being sent, The sequence numberfor each segment is the number of the byte carried in that segment, [A] last [B] first [C] None is correct D middle

b

The OSI model consists of layers, [A] eight P] seven [C] [D] three

b

The domains define registered hosts according to their generic behavior, [A] none is correct [B] generic [C] country D inverse

b

The second phase of JPEG is. [A] data compression [B] quantization [C] none is correct [D] DCT transformatio

b

Urgent data requires the urgent pointer Held as well as the URG bit in the field, [A] sequence number [B] control [C] offset [d] None is correct

b

What are general functions of router? [A] Determine the next node to receive the message [B] All are correct [C] Store and forward packets D Find path for p

b

What is the data unit used in Internet Protocol (IP)? [A] Frame [B] Datagram [C] Message D Segment

b

Which one(s) is (are) routing algorithm(s)for IP? [A] None of them [B] Both (Distance vector algorithms (DVA)) and (Link-state algorithms (LSA)) [C] Distance vector algorithms (DVA) D Link-state algorithms (LSA)

b

A datagram is fragmented into three smaller datagrams, Which of the following is true? A. none is correct B. The more fragment bit is set to Ofor all three datagrams. C. The identification field is the same for all three datagrams. D. The do not fragment bit is set to 1 for all three datagrams

c

A three-character data frame: A FLAG B when framing methods using byte stuffing, the output will be [A] A FLAG FLAG B [B] A B FLAG FLAG [C] A ESC FLAG B D A B ESC FLAG

c

A user needs to send the server some information. The request line method is [A] PATCH [B] none of them C POST D OPTION

c

Assume that the IP address has only 8 bits; first 5 bits are used for network and the remaining bits are used for host. How many subnets and hosts in each subnets can be addressed? [A] 64 subnets and 32 hosts [B] 64 subnets and 64 hosts [C] 32 subnets and 8 hosts D 32 subnets and 32 hosts

c

Because the sending and the receiving processes may not write or read data at the same speed, TCP [A] speeds up the slower process [B] none is correct [C] uses buffers D slows down the faster p

c

Bridges work in the layers. [A] network and transport [B] data link and network [C] physical and data link D none is correct

c

In a Datagram networks, [A] No state about end-to-end connections at the routers [B] Packets may take different paths for the same source-destination pair [C] All are correct [D] No call setup at network lay

c

Maximum number of data flow through in N-port switch (LAN switch L2): [A] N-1 IB] N/4 [C] N/2 [D] N

c

NAT table in router [A] Store the IP address without the port number [B] None of them [C] Store pairs of the IP address of the host with the port number in form of (IP address, port #) D Store the MAC addresses w

c

NAT used at the router to [A] Translate the IP address to MAC address [B] All of them [C] translate the port number of the host In the subnet side to the port number outside the subnet D translate the IP address of hosts in the subnet to the IP addre

c

This command identifies the sender of the message, [A] RCPTTO [B] HELO [C] MAIL FROM [D] none of them

c

Those five primitives (Operations): LISTEN, CONNECT, RECEIVE, SEND, and DISCONNECT are for implementing [A] Flow control in the Transport Layer [B] Connectionless services in the Transport Layer [C] None of these D Connection-Oriented services in the Transport Lay

c

What is the combination of an iP address and a port number called? [A] A checksum [B] Asequence number [C] A socket D A data offset

c

What is the protocol that network devices (for example: modem ADSL) use to assign IP address to PCs in LAN automatically? [A] IGRP IB] HTTP [C] DHCP D OSPF

c

What is the service that the UDP protocol provides? [A] Error detection [B] Flow control [C] None is correct D Guaranteed delivery

c

Which part of the mail created by the UA(User Agent) contains the sender and receiver names? [A] envelope [B] address [C] header D none of them

c

An HTTP request message always contains [A] a status line, a header, and a body [B] a header and a body [C] none is correct D a request line and a head

d

In resolution, the resolver expects the server to supply the final answer, [A] none is correct [B] iterative [C] straight [D] recursive

d

In the encoding scheme, 24 bits become 4 characters, and eventually are sent as 32 bits, [A] binary [B] 8 bit [C] none is correct [D] base 64

d

Relating to CRC, a sequence of bits 100101 can be presented as polynomial [A] None of them [B] xA3+x^2+1 [C] x^2+x+1 D x^5+x^2+1

d

The advantage of UDP is [A] Providing congestion control [B] Providing reliable communication [C] None is correct D Fasterthanthe TCP

d

The local host and the remote host are defined using IP addresses. To define the processes, we need second identifiers called [A] Transport number [B] none of them [C] UDP addresses D Port number

d

Those fallowings: a) Slow start b) Congestion avoidance c) Fast retransmit d) Fast recovery, are mechanisms of. [A] TCP flow control [B] All of them C UDP congestion control D TCP congestion control

d

What is the default subnet mask for a Class C network? [A] 255.255.0.0 [B] 255.0.0.0 C 0.0.0.225 D 255.255.255.0

d

Which field in the IP header is used to prevent an IP packet from continuously looping through a network? [A] Identifier [B] Header Checksum [C] Hop Count [D] Time-to-Live (TTL)

d

Which of the following statement is correct? [A] Half-Duplex: Communications that can go only one direction [B] Full-Duplex: Communications that can go only one direction [C] Half-Duplex: Communications in Which both sender and receiver can sen dat the same time [D] Full-Duplex: Communications in Which both sender and receiver can send at the same time

d

Flow control, [A] is a type of Error Detection [B] ensures the sender does not too much data that may overwhelm the receiver [C] None of them D controls the congestion of network

b