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Computer Networks Viva Questions
1. The application layer is ___________ of the OSI model.
Layer 7
2. What is the use of HTTP?
Hypertext Transfer Protocol (HTTP) is used to transfer files that make up the web pages of the World Wide Web.
.
3. Which is the most popular network service?
E-mail, the most popular network service.
4. FTP requires ___________ connection(s) between client and server to successfully transfer files.
To successfully transfer files, FTP requires two connections between the client and the server: one for commands
and replies and another for the actual file transfer.
5. What is the use of DHCP?
The Dynamic Host Configuration Protocol (DHCP) enables clients on a network to obtain IP addresses and other
information from a DHCP server.
6. Which connection is made using Telnet?
A connection using Telnet is called a VTY session, or connection.
7. Is eBay a peer-to-peer or client/server application?
eBay is a client/server application. eBay is implemented as a web server that responds to web client (browser)
requests using HTTP.
8. In the client/server model, the device requesting the service is referred to as the ___________.
Client.
9. DHCP allows the automation of what?
Assignment of IP addresses, subnet masks, and default gateway. The protocol automates the assignment of IP
addresses, subnet masks, gateway, and other IP networking parameters.
10. What does FTP stand for, and what is it used for?
FTP stands for File Transfer Protocol. It is used to move files on the network. FTP was developed to allow file
transfers between a client and a server.
11. Which form of communication is a real-time, text-based communication type used between two or more people
who use mostly text to communicate?
Instant messaging is both text based and real time.
12. Rules that govern the process of network communication are called ______________.
Protocols
13. Copper cables and fiber-optic cables are two types of network ___________________.
Media
14. Symbols that graphically represent network devices and media are called ___________.
Icons
15. Give reasons why circuit-switched, connection-oriented technologies rejected when the Internet was being
developed?
 Early circuit-switched networks did not automatically establish alternative circuits in the event of circuit
failure.
 Circuit-switched technologies required that an open circuit between network endpoints be established even
if data was not being actively transferred between locations.

The establishment of simultaneous open circuits for fault tolerance is costly.
16. Give reasons why a packet-switched, connectionless data communications technology used when developing the
Internet?
 It can rapidly adapt to the loss of data transmission facilities.
 It efficiently utilizes the network infrastructure to transfer data.
 Data packets can travel multiple paths through the network simultaneously.
17. A _____________ is a device that helps direct messages between networks.
Router
18. Which OSI layer is associated with IP addressing?
IP addressing is a concern of the OSI network layer (Layer 3).
19. The elements of communication include a message source, a message destination, and a ___________________,
or medium, to transport the message.
Channel
20. Which type of addressing is found at the OSI Layer 2?
A MAC address is the physical address burned on to the OSI Layer 2 network interface card.
21. Which term describes a specific set of rules that determine the formatting of messages and the process of
encapsulation used to forward data?
A protocol describes a specific set of rules for communication, including message formatting and encapsulation.
22. A limited-use protocol owned by a company is considered to be _________________________.
Proprietary
23. Which protocol is associated with Layer 4 of the OSI model?
TCP
24. The device that connects a device to the media is called a/an _________________________.
NIC, or network interface card
25. A device that moves data between networks is a _______________.
Router
26. What is the process for interweaving multiple data streams onto one shared communication channel or network
medium?
Multiplexing
27. IP addressing is associated with which layer?
IP addressing is an OSI Layer 3 function.
28. What is the correct “top down” order of the OSI model?
The correct order is application, presentation, session, transport, network, data link, physical.
29. Which layer of the OSI model is concerned with end-to-end message delivery over the network?
End-to-end message delivery is the concern of OSI Layer 4, the transport layer.
30. Which port number is used by HTTP?
Port 80 is the standard port number used with HTTP
31. Which characteristics are parts of TCP?
TCP is a reliable, connection-oriented protocol.
32. What is the purpose of transport layer port numbers?
Port numbers allow you to track multiple conversations generated by the same host using the same IP address.
33. In networking terms, what is reliability?
Reliability means ensuring that each segment that the source sends arrives at the destination.
34. List three network applications that use TCP.
Web browsing, e-mail, file transfer.
35. List three network applications that use UDP.
DNS, video streaming, Voice over IP (VoIP).
36. Which protocol provides connectionless network layer services?
IP provides connectionless network layer services.
.
37. What are three pieces of information about a route that a routing table contains?
A routing table contains the next-hop, metric, and destination network address. Routers do not need the source
address, last hop, or default gateway to find a path to a network.
38. What is the name of the process of removing the OSI Layer 2 information from an IP packet?
Decapsulation.
39. Why is IP “media independent”?
IP encapsulates OSI Layer 4 data. IP can carry voice, video, and other types of data, but “media independent” refers
to the OSI Layer 1 medium that carries the data across the networks.
40. TCP is a __________ layer protocol.
Transport
41. How many bits are in an IPv4 address?
There are four octets (8 bits each) in an IPv4 address.
42. Copper and fiber-optic cable are examples of ____________, which is used to carry the communication signal.
Physical media
43. What is the purpose of encoding?
Encoding represents the data bits by using different voltages, light patterns, or electromagnetic waves as they are
placed onto the physical media.
44. What two signaling methods use voltage to encode bits?
NRZ (non-return to zero) and Manchester.
45. What best describes the purpose of the physical layer?
The chief purpose of the physical layer is to define the functional specifications for links between end systems and
the electrical, optical, and radio signals that carry data.
46. What is the most common Unshielded Twisted Pair (UTP) connector type?
RJ-45
47. Through what process does UTP cable help to avoid crosstalk?
Crosstalk is reduced by the twisting of cables in the UTP (unshielded twisted-pair) cable. UTP has no cladding,
shielding, or grounding points.
48. What is the required order of wires in a connector called?
Pinout
49. What are the advantages of using fiber-optic cable over copper cable?
 Immunity to electromagnetic interference
 Longer maximum cable length
 Greater bandwidth reception and decoding requirements
 Antenna design.
50. The physical media most susceptible to security breaches is ____________.
Wireless. Because wireless is open to anyone with a wireless receiver, it is more susceptible to security breaches
than copper or fiber-optic media.
51. What is the purpose of cladding in fiber-optic cables?
Cladding helps prevent light loss.
52. A _______cable is also known as a Cisco cable because it is generally used as a connection to Cisco equipment.
Rollover cable
53. What is synchronization?
Synchronization between devices allows them to know when frames begin and end.
54. Which command turns on a router interface?
Router (config-if)#no shutdown
55. What is the purpose of the IOS enable secret command?
To allow a user to enter a password that will be encrypted.
56. Which command will display statistics for all interfaces configured on a router?
Router# show interfaces
57. What command will display a list of commands available for viewing the status of the router?
Router# show ?
58. An administrator configures a new router and names it Lab1. The administrator needs to set a password that will
be required to establish a console session with the router. What command should be issued by the administrator to
set the console password to CISCO?
Lab1 (config) # line con 0
Lab1 (config-line)# login
Lab1 (config-line)# password CISCO
59. What type of cable is used to initially configure a router?
A rollover cable connected to the serial port of a computer is used.
60. What do routers use to select best paths for outgoing data packets?
Routing tables
61. What is setup mode?
Setup mode allows you to configure a router by answering a series of questions posed to you.
62. What is a configuration file?
Configuration file contain the Cisco IOS Software commands used to customize the functionality of a cisco device.
63. What are the methods to access CLI?
 Console Port
 Auxiliary Port
 Telnet
64. Explain Privileged Executive Mode?
Privileged exec mode is identified by the prompt ending with the # symbol. It is used by the network administrator
for the execution of configuration and management commands.
65. Explain the error messages: Invalid input?
IOS returns a caret “^” symbol to indicate where the command interpreter cannot decipher the command.
66. How can we take help when configuring?
Enter a question mark (?) at any prompt.
67. Which command is used to restore ‘Default router factory name’?
Adil# no hostname
Router#
68. What are the different modes used in configuring a router?
 User Executive Mode
 Privileged Exec Mode
 Global Configuration Mode
69. Which device forms boundaries between the Broadcast domains?
Router
70. Which command turns on a router interface?
Router (config-if) # no shutdown
71. What is IOS?
Internetworking Operating System.
72. What is the difference between start-up and Running configuration?
Start-up configuration is used as the backup configuration and loaded when the device is started while running
configuration is used during the current operation of the device.
73. Explain user Executive mode?
A mode that is very limited in scope, allowing basically only “viewing” types of IOS commands.
74. Which command is used to move from ‘Privileged Execution Mode’ to ‘User Execution Mode’?
Router # disable
75. Ping message is a …………………..
Unicast message
76. ARP message is a ……………………
Broadcast message
77. What is the difference between Hub and Switch?
Hub is a layer 1 non-buffering device. Switch is a layer 2 buffering device and it makes collision domains.
78. What is the need for Internet?
When two devices are connected in a network, ARP packets traverse between the two computers. ARP packets are
broadcast packets; they will traverse to each computer in a network, which consumes a sufficient bandwidth. In
order to save this bandwidth, routers are used. Routers not only divide a large single network into smaller networks
but also stop broadcast messages. ARP message cannot pass through router so it saves a lot of bandwidth. (Note:
This is the most valid reason that supports this argument however not the only reason of making internet)
79. What is the purpose of login command?
Login command prevents Telnet access to the device without first requiring authentication.
80. What is the purpose of banner?
Banners are vital to provide a method for declaring that only authorized personnel should attempt to gain entry into
the device. They can be an important part of the legal process in the event that someone is prosecuted for breaking
into the device.
81. What is the command used to copy running configuration to NVRAM?
Router # copy run start
82. Which command is used to encrypt the plain passwords in configuration file?
Service password-encryption
83. What is the difference between ‘enable secret password’ and ‘enable password’?
Enable secret password is encrypted and enable password is in plain text.
84. What are the ‘VTY’ lines?
Virtual Teletype Lines used for telnet into a router.
85. Which password is encrypted by default?
Enable Secret
86. Will login banner be displayed if console password is not set?
No, because login banner is associated with console password.
87. What is NVRAM?
Non-volatile random access memory. Data will not be deleted in case of power shut down.
88. What does this error mean? “Physical Link is administratively down.”
Link is always administratively down by default. “No shutdown” command is used to activate the link.
89. What is the default factory name for switch?
Switch
90. Which command is used to stop RIP routing updates to exit out an interface but still allow the interface to
receive RIP route updates?
Router (Config-router)#passive-interface s0
91. What are distance-vector and link-state routing protocols?
 Distance-vector sends its complete routing table out all active interfaces on periodic time intervals.
 Link-state sends updates containing the state of its own links to all routers in the internetwork.
92. 120 in [120/1] is ___
Administrative distance
93. Which command will create a dynamic pool lab that will provide you with 30 global addresses?
ip nat pool lab 171.16.10.65 171.16.10.94 netmask 255.255.255.0
94. What command will be used in NAT for address before translation?
Inside local
95. What command will be used in NAT for address after translation?
Inside global
96. Which command would you place on interface on private network?
Ip nat inside
97. Which command would you place on interface connected to the internet?
Ip nat outside
98. Pat Address Translation is also termed what?
NAT Overload
99. Which are considered the three methods of NAT?
 Static
 Dynamic
 Overload
100. What are advantages of using NAT?
 Conserves legally registered addresses.
 Increases flexibility when connecting to the internet.
 Reduces address overlap occurrence.