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