Computer networking theory midterm

Check all of the services below that are provided by the TCP protocol. a. Reliable data delivery. b. In-order data delivery. c. A guarantee on the maximum amount of time needed to deliver data from sender to receiver. d. A congestion control service to ensure that multiple senders do not overload network links. e. A guarantee on the minimum amount of throughput that will be provided between sender and receiver. f. A flow-control service that ensures that a sender will not send at such a high rate so as to overflow receiving host buffers. g. A byte stream abstraction, that does not preserve boundaries between message data sent in different socket send calls at the sender. h. A message abstraction, that preserves boundaries between message data sent in different socket send calls at the sender.

Reliable data delivery. In-order data delivery. A congestion control service to ensure that multiple senders do not overload network links. A flow-control service that ensures that a sender will not send at such a high rate so as to overflow receiving host buffers. A byte stream abstraction, that does not preserve boundaries between message data sent in different socket send calls at the sender.

When we say that the Internet is a "network of networks," we mean? Check all that apply (hint: check two or more)? a. The Internet is the largest network ever built. b. The Internet is made up of a lot of different networks that are interconnected to each other. c. The Internet is the fastest network ever built. d. The Internet is made up of access networks at the edge, tier-1 networks at the core, and interconnected regional and content provider networks as well.

The Internet is made up of a lot of different networks that are interconnected to each other. The Internet is made up of access networks at the edge, tier-1 networks at the core, and interconnected regional and content provider networks as well.

Which of the characteristics below are associated with a P2P approach to structuring network applications (as opposed to a client-server approach)? a. There is a server that is always on. b. There is not a server that is always on. c. There is a server with a well-known server IP address. d. A process requests service from those it contacts and will provide service to processes that contact it. e. HTTP uses this application structure

There is not a server that is always on. A process requests service from those it contacts and will provide service to processes that contact it.

The transport layer sits on top of the network layer, and provides its services using the services provided to it by the network layer. Thus it's important that we know what is meant by the network layer's "best effort" delivery service. True or False: The network layer's best-effort delivery service means that IP makes its "best effort" to deliver segments between communicating hosts but it makes no guarantees. In particular, it does not guarantee segment delivery, it does not guarantee orderly delivery of segments, a t does not guarantee the integrity of the data in the segments.

True

Suppose a packet is L = 1500 bytes long (one byte = 8 bits), and link transmits at R = 1 Gbps (i.e., a link can transmit bits 1,000,000,000 bits per second). What is the transmission delay for this packet? a. .000012 secs b. .00012 secs c. .0000015 secs d. .0015 secs e. 666,666 secs

.000012 secs

Which of the following descriptions below correspond to a "nuts-and-bolts" view of the Internet? Select oneor more of the answers below that are correct. [Hint: more than one of the answers below are correct] a. A collection of billions of computing devices, and packet switches interconnected by links. b. A platform for building network applications. c. A "network of networks". d. A place I go for information, entertainment, and to communicate with people. e. A collection of hardware and software components executing protocols that define the format and the order of messages exchanged between two or more communicating entities, as well as the actions taken on the transmission and/or receipt of a message or other event

A collection of billions of computing devices, and packet switches interconnected by links. A "network of networks" A collection of hardware and software components executing protocols that define the format and the order of messages exchanged between two or more communicating entities, as well as the actions taken on the transmission and/or receipt of a message or other event

Check all of the services below that are provided by the UDP protocol. Reliable data delivery. In-order data delivery A guarantee on the maximum amount of time needed to deliver data from sender to receiver. A congestion control service to ensure that multiple senders do not overload network links. A guarantee on the minimum amount of throughput that will be provided between sender and receiver. A flow-control service that ensures that a sender will not send at such a high rate so as to overflow receiving host buffers. A byte stream abstraction, that does not preserve boundaries between message data sent in different socket send calls at the sender. A message abstraction, that preserves boundaries between message data sent in different socket send calls at the sender

A message abstraction, that preserves boundaries between message data sent in different socket send calls at the sender

Match the name of an Internet layer with unit of data that is exchanged among protocol entities at that layer, using the pulldown menu.

Application layer = Message Transport layer = Segment Network layer = Datagram Link layer = Frame Physical layer = Bit

Which of the following are advantages of using a web cache? Select one or more answers. a. Caching generally provides for a faster page load time at the client, if the web cache is in the client's institutional network, because the page is loaded from the nearby cache rather than from the distant server. b. Caching allows an origin server to more carefully track which clients are requesting and receiving which web objects. c.. Overall, caching requires fewer devices/hosts to satisfy a web request, thus saving on server/cache costs. d. Caching uses less bandwidth coming into an institutional network where the client is located, if the cache is also located in that institutional network.

Caching generally provides for a faster page load time at the client, if the web cache is in the client's institutional network, because the page is loaded from the nearby cache rather than from the distant server. Caching uses less bandwidth coming into an institutional network where the client is located, if the cache is also located in that institutional network.

Match the access network with the approximate speeds that a subscriber might experience. (Note: if you look these up, do so in the 8E textbook, slides, or video -- not in the 7E or earlier versions, since link access speeds are always increasing over the years).

Ethernet = Wired. Up to 100's Gbps per link. 4G cellular LTE = Wireless. Up to 10's Mbps per device. 802.11 WiFi = Wireless. 10's to 100's of Mbps per device. Cable access network = Wired. Up to 10's to 100's of Mbps downstream per user. Digital Subscriber Line = Wired. Up to 10's of Mbps downstream per user.

Match the function of a layer in the Internet protocol stack to the name of the layer implementing that function.

Protocols that are part of a distributed network application. = Application Layer Transfer of data between one process and another process (typically on different hosts). = Transport layer Delivery of datagrams from a source host to a destination host (typically). = Network layer Transfer of data between neighboring network devices. = Link layer Transfer of a bit into and out of a transmission media. = Physical layer

Which of the characteristics below are associated with the technique of packet switching? Select all correct answers. [Hint: more than one of the answers is correct]. a. Reserves resources needed for a call from source to destination. b. Resources are used on demand, not reserved in advance. c. Data may be queued before being transmitted due to other user's data that's also queueing for transmission. d. Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM) are two approaches for implementing this technique. e. Congestion loss and variable end-end delays are possible with this technique. f. This technique is used in the Internet. g. This technique was the basis for the telephone call switching during the 20th century and into the beginning of this current century.

Resources are used on demand, not reserved in advance. Data may be queued before being transmitted due to other user's data that's also queueing for transmission. Congestion loss and variable end-end delays are possible with this technique. This technique is used in the Internet.

Match the description of a security defense with its name

Specialized "middleboxes" filtering or blocking traffic, inspecting packet contents inspections. = Firewall Provides confidentiality by encoding contents = Encryption Used to detect tampering/changing of message contents, and to identify the originator of a message = Digital signatures Limiting use of resources or capabilities to given users. = Access control Proving you are who you say you are. = Authentication

Which of the characteristics below are associated with a client-server approach to structuring network applications (as opposed to a P2P approach)? a. There is a server that is always on. b. There is not a server that is always on. c. There is a server with a well-known server IP address. d. A process requests service from those it contacts and will provide service to processes that contact it. e. HTTP uses this application structure.

There is a server that is always on. There is a server with a well-known server IP address. HTTP uses this application structure

Match the description of each component of packet delay to its name in the pull down list.

Time needed to perform an integrity check, lookup packet information in a local table and move the packet from an input link to an output link in a router. = Processing delay Time spent waiting in packet buffers for link transmission. = Queueing delay Time spent transmitting packets bits into the link. = Transmission delay Time need for bits to physically propagate through the transmission medium from end one of a link to the other. = Propagation delay

What is the maximum throughput achievable between sender and receiver in the scenario shown below? a. 1.5 Mbps b. 10 Mbps c. 11.5 Mbps

a. 1.5 Mbps

Consider the circuit-switched network shown in the figure below, with four circuit switches A, B, C, and D. Suppose there are 20 circuits between A and B, 19 circuits between B and C, 15 circuits between C and D, and 16 circuits between D and A. What is the maximum number of connections that can be ongoing in the network at any one time? a. 70 b. 20 c. 16 d. 39 e. 31

a. 70

Which of the following physical layer technologies has the highest transmission rate and lowest bit error rate in practice? a. Fiber optic cable b. Coaxial cable c. Twisted pair (e.g., CAT5, CAT6) d. 802.11 WiFi Channel e. Satellite channel f. 4G/5G cellula

a. Fiber optic cable

Choose one of the following two definitions that makes the correct distinction between routing versus forwarding. a. Forwarding is the local action of moving arriving packets from router's input link to appropriate router output link, while routing is the global action of determining the source-destination paths taken by packets b. Routing is the local action of moving arriving packets from router's input link to appropriate router output link, while forwarding is the global action of determining the source-destination paths taken by packets.

a. Forwarding is the local action of moving arriving packets from router's input link to appropriate router output link, while routing is the global action of determining the source-destination paths taken by packets.

Which of the definitions below describe what is meant by the term "encapsulation"? a. Computing the sum of all of the bytes within a packet and placing that value in the packet header field. b. Determining the name of the destination host, translating that name to an IP address and then placing that value in a packet header field. c. Taking data from the layer above, adding header fields appropriate for this layer, and then placing the data in the payload field of the "packet" for that layer. d. Receiving a "packet" from the layer below, extracting the payload field, and after some internal actions possibly delivering that payload to an upper layer protocol. e. Starting a transport layer timer for a transmitted segment, and then if an ACK segment isn't received before the timeout, placing that segment in a retransmission queue

c. Taking data from the layer above, adding header fields appropriate for this layer, and then placing the data in the payload field of the "packet" for that layer.