CPS 470 MIDTERM
Which of the following descriptions below correspond to a "nuts-and-bolts" view of the Internet? Select one or more of the answers below that are correct. [Hint: more than one of answers below are correct]. [ ] A platform for building network applications. [ ] A collection of billions of computing devices, and packet switches interconnected by links. [ ] 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 place I go for information, entertainment, and to communicate with people. [ ] A "network of networks".
[X] A collection of billions of computing devices, and packet switches interconnected by links. [X] 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. [X] A "network of networks".
Which of the following descriptions below correspond to a "services" view of the Internet? Select one or more of the answers below that are correct below that are correct. [Hint: more than one of answers below are correct]. [ ] A place I go for information, entertainment, and to communicate with people. [ ] A collection of billions of computing devices, and packet switches interconnected by links. [ ] 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 "network of networks". [ ] A platform for building network applications.
[X] A place I go for information, entertainment, and to communicate with people. [X] A platform for building network applications.
What do we mean when we say "HTTP is stateless"? In answering this question, assume that cookies are not used. Select the single answer that applies. [ ] An HTTP client does not remember the identities of the servers with which it has interacted. [ ] The HTTP protocol is not licensed in any country. [ ] We say this when an HTTP server is not operational. [ ] An HTTP server does not remember anything about what happened during earlier steps in interacting with this HTTP client. [ ] An HTTP client does not remember anything about what happened during earlier steps in interacting with any HTTP server.
[X] An HTTP server does not remember anything about what happened during earlier steps in interacting with this HTTP client.
Which of the following are advantages of using a web cache? Select one or more answers. [ ] Caching uses less bandwidth coming into an institutional network where the client is located, if the cache is also located in that institutional network. [ ] Overall, caching requires fewer devices/hosts to satisfy a web request, thus saving on server/cache costs. [ ] Caching allows an origin server to more carefully track which clients are requesting and receiving which web objects. [ ] 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.
[X] Caching uses less bandwidth coming into an institutional network where the client is located, if the cache is also located in that institutional network. [X] 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.
Choose one the following two definitions that make the correct distinction between routing versus forwarding: [ ] Ro=outing is the local action of moving arriving from routher's input link to appropiate router output link, while forwarding is the global action of determining the source-destination path taken by packets. [ ] Forwarding is the local action of moving arriving packets from routher's input link to appropiat router output link, while routing is the global action of determining the source-destination paths taken by packets.
[X] Forwarding is the local action of moving arriving packets from routher's input link to appropiat router output link, while routing is the global action of determining the source-destination paths taken by packets.
Which of the characteristics below are associated with a client-server approach to structuring network applications (as opposed to a P2P approach)? [ ] HTTP uses this application structure. [ ] There is a server that is always on. [ ] There is a server with a well-known server IP address. [ ] 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.
[X] HTTP uses this application structure. [X] There is a server that is always on. [X] There is a server with a well-known server IP address.
Which of the characteristics below are associated with the technique of packet switching? Select all correct answers [ ] Reserves resources needed for a call from source to destination [ ] Resources are used on demand, not reserved in advance [ ] Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM) are two approaches for implementing this technique [ } Data may be queuedd before being transmitted due to other user's ddata that's also queueing for transmission. [ ] Congestion loss and variable end-end delays are possible with this technique.
[X] Resources are used on demand, not reserved in advance [X] Data may be queuedd before being transmitted due to other user's ddata that's also queueing for transmission. [X] Congestion loss and variable end-end delays are possible with this technique.
Which one is correct in the following descriptions? [Hint: more than one of answers below are correct]. [ ] Wi-Fi can support 100's Mbps transmission rate [ ] Ethernet cable (category 6) can support 10 Gbps transmission rate [ ] telephone line (i.e., digital subscriber line (DSL)) can 24-52 Mbps downstream transmission rate, and 3.5-16 Mbps upstream transmission rate [ ] television cable can support 40 Mbps - 1.2 Gbps downstream transmission rate, and 30-100 Mbps upstream transmission rate [ ] 4G cellular radio can support 10's Mbps transmission rate []Fiber optic cable can support 10's-100's Gbps transmission rate
All of them are true
Transfer of data between neighboring network devices
Link layer
ØDelivery of datagrams from a source host to a destination host (typically).
Network layer
Transfer of a bit into and out of a transmission media
Physical layer
Transfer of data between one process and another process (typically on different hosts).
Transport layer
Which of the definitions below describe what is meant by the term "encapsulation"? [ ] 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. [ ] 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. [ ] 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. [ ] Computing the sum of all of the bytes within a packet and placing that value in the packet header field. [ ] Determining the name of the destination host, translating that name to an IP address and then placing that value in a packet header field.
[X] 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
Which of the following human scenarios involve a protocol (recall: "Protocols define the format, order of messages sent and received among network entities, and actions taken on message transmission, receipt")? Select one or more answers below that are correct. Hint: more than one of answers below are correct. [ ] A person reading a book. [ ] A person sleeping. [ ] Two people introducing themselves to each other. [ ] A student raising her/his hand to ask a really insightful question, followed by the teaching acknowledging the student, listening carefully to the question, and responding with a clear, insightful answer. And then thanking the student for the question, since teachers love to get questions. [ ] One person asking, and getting, the time to/from another person.
[X] Two people introducing themselves to each other. [X] A student raising her/his hand to ask a really insightful question, followed by the teaching acknowledging the student, listening carefully to the question, and responding with a clear, insightful answer. And then thanking the student for the question, since teachers love to get questions. [X] One person asking, and getting, the time to/from another person.
Does the client have a cached copy of the object being requested? [ ] No, because a client would not request an object if it had that object in its cache. [ ] There's not enough information in the header to answer this question. [ ] Yes, because HTTP 1.1 is being used. [ ] Yes, because this is a conditional GET, as evidenced by the If-Modified-Since field.
[X] Yes, because this is a conditional GET, as evidenced by the If-Modified-Since field.
Will the web server close the TCP connection after sending this message? [ ] There's not enough information in the response message to answer this question. [ ] Yes, the server will close this connection because version 1.0 of HTTP is being used, and TCP connections do not stay open persistently. [ ] Yes, because the HTTP response indicated that only one object was requested in the HTTP GET request. [] No, the server will leave the connection open as a persistent HTTP connection
[X] Yes, the server will close this connection because version 1.0 of HTTP is being used, and TCP connections do not stay open persistently.
Which physical media can be used as the transmission link within the access network (e.g., home access network and enterprise network)? [Hint: more than one of answers below are correct]. [ ] telephone line (i.e., digital subscriber line (DSL)). [ ] fiber optic cable. [ ] ethernet cable. [ ] radio (i.e., Wi-Fi) . [ ] television cable (i.e., coaxial cable).
[X] ethernet cable. [X] radio (i.e., Wi-Fi) .
Which physical media is used as the transmission link (yellow colored) within & across the ISPs? [ ] telephone line (i.e., digital subscriber line (DSL)). [ ] fiber optic cable. [ ] ethernet cable. [ ] radio (Wi-Fi ) . [ ] television cable (i.e., coaxial cable).
[X] fiber optic cable.
Which physical media can be used as the transmission link within the wide-area mobile access network (i.e., the left upper corner network with a base station in the figure)? [Hint: more than one of answers below are correct]. [ ] radio (4G). [ ] television cable (i.e., coaxial cable). [ ] radio (Wi-Fi) . [ ] radio (5G).
[X] radio (4G). [X] radio (5G).
Which physical media can be used as the transmission link (red colored) between the ISP (e.g., ATT, Spectrum, Comcast, etc.) to the access network (e.g., home access network and enterprise network)? [Hint: more than one of answers below are correct]. [ ] telephone line (i.e., digital subscriber line (DSL)). [ ] fiber optic cable. [ ] ethernet cable. [ ] radio (Wi-Fi) . []television cable (i.e., coaxial cable).
[X] telephone line (i.e., digital subscriber line (DSL)). [X] fiber optic cable. [X]television cable (i.e., coaxial cable).
Which of the following are changes between HTTP 1.1 and HTTP/2? Note: select one or more answers. [ ] HTTP/2 allows objects in a persistent connection to be sent in a client-specified priority order. [ ] HTTP/2 allows a large object to be broken down into smaller pieces, and the transmission of those pieces to be interleaved with transmission other smaller objects, thus preventing a large object from forcing many smaller objects to wait their turn for transmission. [ ] HTTP/2 provides enhanced security by using transport layer security (TLS). [ ] HTTP/2 has many new HTTP methods and status codes.
[X]HTTP/2 allows objects in a persistent connection to be sent in a client-specified priority order. [X]HTTP/2 allows a large object to be broken down into smaller pieces, and the transmission of those pieces to be interleaved with transmission other
Transport layer
segment
Physical layer
bit
Network layer
datagram
Link layer
frame
Application layer
message
