computer networks quiz 1

Consider the figure below, showing a link-layer frame heading from a host to a router. There are three header fields shown. Match the name of a header with a header label shown in the figure. (figure shows computer going to H1, H2, and H3 and goes to router)

H1: Link, H2: Network, H3: Transport

processing delay

time needed to perform an integrity check, look up packet information in a local table and move the packet from an input link to an output link in a router

propagation delay

time needed to physically propagate through the transmission medium from end one of a link to another

transmission delay

time spent transmitting packets into the link

queueing delay

time spent waiting in packet buffers for link transmission

conditional http get

to allow server to only send requested object to client if this object has changed since server last sent this object to client

if modified since

to indicate to server that client has cached this object from previous get, and time it was cached

What is the command that can provide end-to-end Internet delay through a list of routers along the path?

traceroute

physical layer

transfer of a bit into and out of a transmission media

link layer

transfer of data between neighboring network devices

transport layer

transfer of data between one process and another process

Computing Packet Transmission Delay(1). 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?

.000012 secs

Computing utlilization (1). Consider the scenario shown below, with four different servers connected to four different clients over four three-hop paths. The four pairs share a common middle hop with a transmission capacity of R = 300 Mbps. The four links from the servers to the shared link have a transmission capacity of RS = 50 Mbps. Each of the four links from the shared middle link to a client has a transmission capacity of RC = 90 Mbps.Assuming that the servers are all sending at their maximum rate possible, what are the link utilizations for the server links (with transmission capacity RS)? Enter your answer in a decimal form of 1.00 (if the utilization is 1) or 0.xx (if the utilization is less than 1, rounded to the closest xx).

1.00

Computing maximum thoughput. Consider the scenario shown below, with 10 different servers (three shown) connected to 10 different clients over ten three-hop paths. The pairs share a common middle hop with a transmission capacity of R = 300 Mbps. The links from the servers to the shared link have a transmission capacity of RS = 90 Mbps. Each of the link from the shared middle link to a client has a transmission capacity of RC = 50 Mbps. What is the end-end maximum throughput on one of the the-hop paths, assuming all servers are sending at the maximum rate possible to their clients?

30 Mbps

What is a network of networks? When we say that the Internet is a "network of networks," we mean? Check all that apply (hint: check two). a. The Internet is made up of a lot of different networks that are interconnected to each other. b. The Internet is the fastest network ever built. c. 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. d. The Internet is the largest network ever built.

a, c

Which of the characteristics below are associated with the technique of packet switching? a. Resources are used on demand, not reserved in advance. b. Reserves resources needed for a call from source to destination. c. Congestion loss and variable end-end delays are possible with this technique. d. This technique is used in the Internet. e. Data may be queued before being transmitted due to other user's data that's also queueing for transmission. f. This technique was the basis for the telephone call switching during the 20th century and into the beginning of this current century.

a, c, d, e

4 components of cookies

request, response, user host, backend database

3 levels of DNS

root, top level domain, authoritative

transport layer unit of data

segment

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

b

physical layer unit of data

bit

Distributed Denial of Service (DDoS)

the attacker controls multiple botnets and has those botnets blast traffic at the target

What is the Internet(1)? Which of the following descriptions below correspond to a "nuts-and-bolts" view of the Internet? a. A place I go for information, entertainment, and to communicate with people. b. A platform for building network applications. c. A "network of networks". d. 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. e. A collection of billions of computing devices, and packet switches interconnected by links.

c, d, e

What is "encapsulation"? Which of the definitions below describe what is meant by the term "encapsulation"? a. Determining the name of the destination host, translating that name to an IP address and then placing that value in a packet header field. b. Computing the sum of all of the bytes within a packet and placing that value in the packet header field. c. 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. d. 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. e. 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.

d

network layer unit of data

datagram

network layer

delivery of datagrams from source host to destination host

IP spoofing

the attacker injects packets into internet with false source address

Which of the characteristics below are associated with the technique of circuit switching? a. Congestion loss and variable end-end delays are possible with this technique. b. This technique is used in the Internet. c. Data may be queued before being transmitted due to other user's data that's also queueing for transmission. d. Resources are used on demand, not reserved in advance. e. Reserves resources needed for a call from source to destination. f. This technique was the basis for the telephone call switching during the 20th century and into the beginning of this current century.

e, f

link layer unit of data

frame

routing

global action of determining source destination paths taken by packets

http is stateless

http server does not remember anything about what happened during earlier steps in interacting with this http client

forwarding

local action: move arriving packets from router's input link to appropriate router output link

worms

malware that can enter a device without any explicit user interaction

viruses

malware that requires some form of user interaction to infect the device

Application Layer unit of data

message

services view of internet

place you go for entertainment, information, and to communicate with people, and a platform for building network applications

application layer

protocols that are part of a distributed network application

packet sniffing

the attacker passively records every copy of packet that is sent back and forth in a wireless network

http get

used by web client to request web server to send the requested object from server to client