ITCS 3146 -Final Exam Review
In bit stuffing, each data frame starts and ends with a special ___ of ___
-sequence -bits
Types of topology
Mesh topology Bus topology Ring topology Star topology Tree topology
The Linux command for displaying the ARP table is _____.
arp -an
ARP stands for Address _____ Protocol.
resolution
Which of the following represent possible uses of a computer network?
-To share storage space among multiple computers -Information sharing among people
The Open Systems Interconnection (OSI) model specifies the ___ of each layer, but does not specify what ___ each layer will use.
-function -protocols
Port forwarding allows traffic flowing from an SSH client to an SSH server to be __ into port __ and then sent across the network in an encrypted tunnel.
-multiplexed -22
The primary goal of the network layer is to transfer packets between the ____ of the data and the _____, possibly via multiple ____
-origin -final destination links
The ___ flag is set to 1 in the TCP IP header to indicate that the sender has no more data to send.
FIN
Which of the following is not a goal of a routing algorithm?
modularity
DNS uses ___ to maintain the mappings it needs.
name servers
Nodes or systems keep an ARP look-up _____ or "cache" to store a mapping between IP addresses and MAC addresses
table
True or False. The data link layer handles MAC addresses, which are assigned by the hardware manufacturer.
true
Metropolitan Area Network (MAN)
cable television connected via co-axial cables
The Internet Protocol (IP) does not provide any ____ guarantees and so it is known as a ___ service.
-reliability -best effort
Domain Name System (DNS) is a service that resolves _____ into ____ .
-Human-readable names -IP addresses
The source address field in the TCP IP header contains the ___ address of the original ___ of the ____
-IP -sender -packet
___ addresses are the future of the Internet Protocol. These addresses use ___ bits. The notation used is ___ groups of ____ digits each separated by colons
-IPv6 -128 -8 -4 hexadecimal
A host identifier (i.e., IP address) is also known as a ___ Service Access Point and a process identifier within a host (i.e., port number) is also known as a ___ Service Access Point. The combination of the two identifiers forms a __
-Network -Transport -socket
Which of the following flags are used during the connection establishment phase of TCP?
-SYN -ACK
Select ALL that apply. What are some things that you can do securely with SSH?
-Transfer files across a network -Execute system commands from a remote location -Perform port forwarding.
Dijkstra's algorithm finds the shortest path between ___ source node(s) and ___ destination node(s) within that network.
-a given -all
Each layer in network software ___ a set of services, which means underlying details are ___ to other layers.
-abstracts -hidden
In the TCP/IP model, the ___ layer covers the same functionality as the application, presentation, and session layers in the OSI model. The Internet layer in the TCP/IP model corresponds with the __ layer in the OSI model. The ___ layer in the TCP/IP model corresponds with the the data link and physical layers in the OSI model.
-application -network -link
The viewing of a webpage on a browser is the result of a conversation between the browser (which acts as a ____ ) and the ___
-client -server
In a ___ model, a central computer is a provider of services and resources and other computers are consumers of those services and resources. In a ___ model computers can be both providers and consumers of data or services
-client-server -peer-to-peer
Select ALL that apply. Which of the following are considered to be mediums of communication?
-co-axial cables -bluetooth -WiFi
A computer network is one that provides ___ among computers, i.e., it is a ___through which computers can exchange ___
-communication -network -data
Transport layer protocols support ___ network usage by multiple ___ processes on the host.
-concurrent -application
Which of the following additional responsibilities does the network layer have?
-congestion control -internetworking
A DNS cache is a temporary ___ that contains a record of recent and attempted ___ to websites or other internet domains
-database -visits
Congestion is when the network gets ___ with more ___ than it can handle.
-flooded -packets
If you are logged into the terminal of a Linux system, the two commands, not including tcpdump, to view the MAC address of that system are ___ and ___
-ifconfig -ip addr ls
A host must be in a ___ or ___ state in order to receive incoming TCP connection requests.
-listen -passive open
The transport layer provides ___ end-to-end communication between hosts and is entirely run on ___ computers.
-logical -host
IPv4 is a _____ layer ____ protocol.
-network -connectionless
The common protocol in the ____ layer that all nodes understand is called the ____ Protocol.
-network -internet
Secure Shell or SSH is a ___ protocol for ___ data that flows between a client and a server.
-network -securing
TCP uses a mechanism called ___ through which the destination/receiver can specify which ___ it is acknowledging and through which the destination node can ___ the original stream of data if needed.
-sequence number -segment reconstruct
The ___ flag is set to 1 in the TCP IP header to indicate that the value in the Acknowledgment number field is the next sequence number that the receiver is expecting.
ACK
Transport layer data ___ examined by nodes in between the source and destination computers.
is not
The Statistics-->Protocol Hierarchy menu item will give you the layout of all of the different packets found by Wireshark.
packets
Given the IP address 171.12.0.0/20, how many least significant bits form the host identifier?
12
A network of computers, smart phones and smart TVs within a home would be classified as a
Local Area Network (LAN)
Every packet that the network layer of any node receives from the link layer is sent up to the transport layer of that node.
false
The length of the UDP header is ___
fixed
When using shortest path routing, the shortest path is calculated and stored in a ___
routing table
IPv4 addresses are ___ bits long and are represented using the ___ notation
-32 -dotted decimal
Elements written in blue font represent
-nodes that have been finalized -nodes to which the shortest distance from the source node has been found
The world wide web is a vast collection of ___, which are named with a ____
-pages -uniform resource locator
A DNS cache becomes ___ when ___ domain names or IP addresses are inserted into it.
-poisoned -unauthorized
In traffic-aware ___, we consider the current ___ and direct traffic away from hotspots.
-routing -traffic
What does it mean when we say that the receiver knows how to de-stuff the received bytes?
The receiver ignores escape bytes inserted when the flag byte occurs in the payload.
A small group of technical support staff consists of a manager and five customer service agents. Every employee has a computer, but the manager's computer is connected to the only printer. Currently, the computers are not networked. So, if an agent wants to print a file, he/she must copy the file to a flash drive and carry it to the manager's computer. To be more efficient, the group has decided to set up a network. Assume that the printer itself is still only connected to the manager's computer. Identify the logical network architecture/model in play.
client server
Routing tables contain one entry for every possible destination IP on the internet. True or False.
false
True or False. Peer layers (i.e., layers with same number on two different computers) in a layered approach communicate directly with one another
false
True or False. The layer 2 Ethernet protocol is unaware of routing and so there is no way for nodes to communicate with nodes in other subnets.
false
True or False. The layer 2 ethernet protocol understands routing.
false
Consider the following URL and identify its constituent parts: https://www.lifewire.com/how-urls-work-2482921 What is the protocol? What is the server name? What is the name of the page being requested?-
https www.lifewire.com how-urls-work-2482921
In Wireshark, you can see that a frame corresponds to the ____ layer and you will be able to see how each protocol that correspond to each layer in the OSI model.
physical
Load ____ is when routers drop packets when congestion is too high.
shedding
Which of the following features may be provided by transport layer protocols?
-flow control -congestion control
If the SYN flag is set to 1 in a segment sent by host A to host B, the sequence number field indicates the ___ sequence number that host ____ will use in segments that it sends to host _____ . If the SYN flag is set to 0 in a segment sent by host A to host B, the sequence number field indicates the ____ in the segment.
-initial -A -B -sequence number of the first data byte
IPv6 supports a ___ address than IPv4 and has a ____ header than IPv4.
-larger -simpler
A subnet with a ___ prefix is less specific than one with a ___ prefix.
-shorter -longer
TCP uses a mechanism called the ___ protocol for flow control
-sliding window
The ____ or sender component of a network generates the data to be sent and uses a ____ component, which converts the data into signals that can be carried by a ___ medium.
-source -transmitter -communication
Transmission Control Protocol or TCP provides a ___ service, which is ____ service.
-stream -a reliable connection-oriented
In traffic ____ , routers track the network state and determine when ___ will occur
-throttling -congestion
Data in a layered approach travels from the ____ to the ___ layer on the sender side, but travels from the ___ to the ___ layer on the receiver side.
-top -bottom -bottom -top
In a ring topology with n computers where bi-directional communication is allowed, what is the minimum number of computers that must fail to make at least one computer (other than the failed computer) no longer reachable?
2 computers
In a postal network, every sender and receiver is uniquely identified by a postal address. In a plain old telephone network, each telephone is uniquely identified by a telephone number. Similarly, any computer or device that is connected to the Internet is uniquely identified by a/an
IP address
Using the routing table in the following table, where will the IP 192.24.11.100 be forwarded?
L
Wide Area Network (WAN)
multiple devices connected across an entire country, connected wirelessly
User Datagram Protocol (i.e., UDP) is an ____ protocol.
an unreliable connectionless
The command to delete the MAC address used for IP address 10.0.0.8 would be ______
arp -d 10.0.0.8
A gratuitous ARP will force machines on a subnet to update their ARP tables by broadcasting an ARP reply packet not in response to a specific request. What would be the correct way to send a gratuitous ARP on eth0 for 10.0.0.8?
arping -A -I eth0 10.0.0.8
UDP provides limited flow control
false
Proxy servers and firewalls operate at the _____ layer.
transport
If there are multiple matching entries in the routing table, the match with the most specific prefix is chosen. True or False.
true
In a reliable network service, the sender requires an acknowledgement from the receiver. True or False.
true
Public IP addresses are guaranteed to be unique across the Internet. True or False.
true
Personal Area Network (PAN)
two devices connected via bluetooth
In every iteration, the node with the shortest known distance from the source node is chosen for exploration next.
with the shortest known distance from the source node
For the subnet represented by 171.14.0.0/18, how many least significant bits are used to identify individual hosts?
14
If the IP address range for a subnet is 145.2.12.0 to 145.2.12.255, which is the correct slash notation for this subnet?
145.2.12.0/24
OSI layer with the protocols
Application Layer - HTTP, SMTP, FTP, Telnet Presentation Layer - ASCII, MP3, JPEG, MPEG Session Layer - Netbios Transport Layer - TCP, UDP Network Layer - IP Data Link Layer - Ethernet Physical Layer - Cat5 Cable
OSI Layers and their responsibility
Application Layer - handles the user interface to networking services Presentation Layer - handles formatting the details for the data Session Layer - handles the initiation, maintenance, and termination of the connection Transport Layer - handles the transfer of messages between the sender and the reciever Network Layer - handles the path or route between source and destination through the network Data Link Layer - handles the transmission of data between two nodes Physical Layer - handles the transmission of raw bits over the communication channel
Assume a ring topology with n computers where communication is uni-directional. What is the maximum number of intermediate computers a message between two computers may need to go through?
At most n-2 intermediate computers
Which value (or field) in the IP header (Layer-3) is used to prevent accidental routing loops?
Time to live
If a packet has the "do not fragment" flag set and cannot move any further because it is too large, it will be ____.
dropped
An entry on a system's ARP table is cached until the entry ____ or is manually cleared.
expires
Name resolution performed by DNS is a single step process
false
In any given iteration, nodes to which distances from the source node are as yet unknown are indicated using the value infinity .
infinity
Congestion control is achieved in TCP by adjusting the ___ rate on the sender/source node.
transmission
The IPv4 pseudo-header contents are not part of the UDP header and are only used in the UDP checksum calculation.
true
True or False. An IPv4 address is composed of four octets separated by dots.
true
True or False. It is possible to manually publish ARP entries on one interface for nodes on another interface to allow ARP to reach machines on another subnet.
true
True or False. Wireshark packet captures can be exported.
true
Local Area Network (LAN)
two computers networked within a single room, connected via ethernet cables