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50+ Computer network interview questions

A network is a set of devices that are connected with each other through a link. A network is a collection of devices connected to each other to enable sharing of data and other resources.

Internet is an example of a computer network, that is widely used all over the world. Computer Networks helps to understand the specifications and the dynamics involved in creating and managing a network.

1. What is a network?

A network is a set of devices that are connected with each other through a link. A network is a collection of devices connected to each other to enable sharing of data and other resources. Eg: Internet

2. What do you mean by network topology?

Network topology is a connection layout of the computers over a network. It shows how devices and cables, must be connected to each other with minimum expense of resources. The different types of topologies are:

Bus
Ring
Star
Mesh
Tree, and
Hybrid

3. What are the advantages of Distributed Processing?

The advantages of distributed processing are as follows:

Secure
Supports Encapsulation
Distributed database
Faster Problem solving
Security through redundancy
Collaborative Processing

4. What is the criteria to check the network reliability?

Network reliability means the ability of the network to carry out some operation via a network without any lag.

The reliability of a network can be checked through following factors:

Downtime: The downtime is the time required by the network to recover itself from failure.

Failure Frequency: It is the frequency of a network failure.

Catastrophe: It indicates that the network has been compromised due to some unexpected event such as fire, earthquake.

5. Which are the different factors that affect the security of a network?

The factors that affect network security are:

Unauthorized Access
Viruses

6. Which are the different factors that affect the reliability of a network?

The factors that affect network reliability are:

Frequency of failure
Recovery time of a network after a failure

7. Which are the different factors that affect the performance of a network?

The following factors affect the network performance:

Large number of users
Transmission medium types
Hardware Components used, and
Software requirement

8. What makes a network effective and efficient?

Performance: The transmit time and response time are used to measure a network’s performance.

Reliability: reliability is measured by frequency of failure, lower the failure frequency higher the reliability of a network.

Robustness: robustness specifies the quality of a network.

Security: It specifies how to protect data transmitting over a network from unauthorized access and viruses.

9. What is bandwidth?

The limit range of a network between its upper and lower frequency is called bandwidth. Every signal has a limit of upper range frequency and a limited lower range frequency

10. What is a node and link?

A network is a set of devices that are connected with each other through a link. The physical medium through which the computers are connected is known as a link, while the computers connected are known as nodes.

11. What is a gateway?

A node that is connected with more than one networks is called a gateway or a router. It’s main function is to forward messages from one network to another.

12. What is DNS?

\nDNS stands for Domain Name System. It is a naming system, through which all the resources over the internet are given a name. Thus, it becomes easier to locate a resource over a network. DNS is a naming system which maps the domain
\nnames to their associated IP addresses.
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13. What is DNS forwarder?

A forwarder comes into use with DNS server when it receives the queries that cannot be resolved quickly. So, it forwards those requests to external DNS servers for resolution.

14. What is NIC?

\nNIC or the Network Interface Card, is a peripheral card that is attached to a PC to connect, that PC as a node to a network. Every NIC has its own unique MAC address, and the PC connected via that NIC is identified by the MAC
\naddress of the NIC. NICs were mainly used in desktop computers.
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15. What is the meaning of 10Base-T?

It is a common specification for a cable. With it we can infer that the, specify the data transfer rate is 10Mbps. Base specifies the baseband and T specifies the type of the cable which is a twisted pair.

16. What is NOS in computer networking?

\nNOS is an acronym for Network Operating System. It is specialized software, which is used to provide a network connectivity to a computer. This network connectivity is used to enable communication with other computers and devices.
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Eg: Windows 2000, Windows XP, Linux, etc.

17. What are the different types of networks?

The different types of networks are:

PAN (Personal Area Network): Created for personal use, with a range of 10m personal devices are connected to this network. For example computers, telephones, fax, printers, Bluetooth, etc.
LAN (Local Area Network): Used for a small geographical locations like office, hospital, school, etc. Whenever the connections are all available in the same building, a LAN is used.
CAN (Campus Area Network): CAN as the name suggests, is a connection of devices within a campus area.
MAN (Metropolitan Area Network): Connects devices spanning across cities over a wide geographical area.
WAN (Wide Area Network): Connects devices spanning across countries over a wide geographical area.
GAN (Global Area Network): It is used by the satellites to connect devices over a global area. GAN has the maximum range in all the networks.

18. What is POP3?

POP3 stands for Post Office Protocol version3. It is responsible for accessing the mail service on a client machine. POP3 can work on two modes, the Delete mode and Keep mode.

19. What is a MAC address?

MAC Address or Media Access Control address, is the address of the device at the Media Access Control Layer of Network Architecture. Every device has a unique MAC address.

20. What is IP address?

IP address is a unique 32-bit software address of a computer in a network system. Every computer has its own unique IP Address; it can be used to identify a computer over a network.

21. What is a private IP address?

A private IP address is not valid for use on the internet. If anyone wants to access the internet on these private IPs, then a proxy server or NAT server, must be used.

22. What is public IP address?

A public IP address is an address taken by the Internet Service Provider, which facilitates a communication over the internet.

23. What is APIPA?

APIPA stands for Automatic Private IP Addressing. It is a feature, which found in the Windows operating system.

24. What do you mean by ADS?

ADS stands for Active Directory Structure. It is used to manage the computers and other devices.

ADS allows the network administrators to manage the domains, users and objects within the network.

25. What is RAID?

RAID or Redundant Array of Independent Disks, is a method to provide the feature of fault tolerance by using multiple Hard Disk Drives.

26. What is anonymous FTP?

\nFTP stands for the File Transfer Protocol, it facilitates the transfer of files over a network. Anonymous FTP is used to grant users access to files in public servers. Users which are allowed access to data in these servers do not
\nneed to identify themselves, and can instead log in as an anonymous guest.
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27. What is a protocol?

A protocol is a set of rules. These rules are used to govern all the aspects of information communication. Some common protocols used over a network are HTTP, FTP, SMTP, POP, etc.

28. What are the main elements of a protocol?

The three main elements of a protocol are:

Syntax: Syntax specifies the structure or format of the data. Apart from this, it also specifies the order in which data is presented.

Semantics: It specifies the meaning of each section of bits.

Timing: Timing specifies two characteristics: when and how?

29. What is a link?

A link is provides a connection between two devices. This link may be a physical link, which includes the cables or it may include the protocols used in for communication.

30. Explain Hybrid Topology.

A hybrid topology in a network topology created with a combination of different topologies to form a resulting topology. It provides flexibility as it can be implemented in a different network environment.

In Hybrid Topology, the weakness of a topology is ignored, and its strength is taken into consideration, making the network most secure and reliable.

31. What is the OSI reference model?

The OSI reference model is an ISO standard. It defines a networking framework for implementing the protocols in seven layers.

The seven layers of the OSI model are:

1) Physical Layer, 2) Data Link Layer, 3) Network Layer, 4) Transport Layer, 5) Session Layer, 6) Presentation Layer, and 7) Application Layer.

These seven layers are grouped into three categories, which is depicted as follows:

Network layer: Layer 1, Layer 2 and layer 3.

Transport layer: Layer 4

Application layer. Layer 5, Layer 6 and Layer 7

32. What is the usage of the physical layer in OSI model?

The physical layer in an OSI reference model is used to convert data bits into the electrical signals and vice versa. It is the lowest layer of the model and on this layer, the network devices are setup.

33. Explain the functionality of OSI session layer.

\nOSI session layer provides the protocols and means for two devices on the network to communicate with each other by holding a session. Every communication takes place in the form of a period, known as a session. This layer is
\nresponsible for setting up the session and managing information exchange during the session.
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34. What is the maximum allowed length for a UTP cable?

The maximum allowed length of a UTP cable is 90 to 100 meters.

35. What is RIP?

\nRIP or Routing Information Protocol, is accessed by the routers to send data from one network to another. It is a dynamic protocol which is used to find the best route from the source node to the destination node using the hop count
\nalgorithm.
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36. What do you understand by TCP/IP?

\nTCP/IP is short for Transmission Control Protocol /Internet protocol. It is a set of protocol layers that is designed for exchanging data on different types of networks. Its architecture is different from that of an OSI:ISO
\nreference model.
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37. What is netstat?

A netstat is a command line utility program. It is used to give useful information about the current TCP/IP setting of a connection.

38. What is a ping command?

Ping is a utility program that allows to check the connectivity between the network devices. Devices can be pinged using the IP address or name.

39. What is Sneakernet?

\nSneakernet is a jargon term and is referred to the earliest form of networking where the data is physically transported using removable media. The name is so because of the idea that someone uses shoes(sneakers) to move data around
\nin a network.

40. What is the backbone network?

A backbone network is a centralized infrastructure that is used to distribute different routes and data to various networks. It also handles the management of bandwidth across multiple channels.

41. What is a congested switch?

\nA switch receives packets faster than the shared link. It can accommodate and stores the packets in its memory, for an extended period. This is done through buffer space in case the buffer space is filled then some packets must be
\ndropped. This state is called a congested state. A switch in a congested state is known to be a congested switch.
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42. What is a VPN?

VPN or Virtual Private Network, is a technology that allows creation of a secure tunnel across a network with global access. VPNs allow to establish a secure dial-up connection to a remote server on the internet.

43. What is DoS?

\nA Denial-of-Service attack, is an attempt that prevents the users from accessing the Internet or any other network services. These attacks may come in different forms and are usually done by a group of attackers. A method of doing
\nthis is to overload the system server so it cannot process the legitimate traffic and must be to reset.
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44. What are firewalls?

\nFirewalls are used to protect an internal network from any external attack. The hackers who try to steal data or plant computer viruses can perform these external attacks. Firewalls also prevents other users from external networks
\nfrom gaining access to a private network.
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45. How many layers are there in TCP/IP model?

A TCP/IP model has four basic layers:

Application Layer
Transport Layer
Internet Layer
Network Layer

46. Explain Bus Topology.

\nBus topology is a network connection architecture, in which all the nodes are connected via a single cable known as bus. It acts as a communication medium, if any device wants to send the data to other devices, then it is sent
\nthrough bus.
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Bus topology is useful for a small number of devices.

47. Explain Star Topology

\nIn Star topology all the nodes are connected to a single device known as a central device. It requires more cables compared to other topologies. Therefore, it is more robust as a failure in one cable will only disconnect a specific
\ncomputer and the network will remain unaffected. However, if the central device is damaged, then the whole network fails.
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48. Explain Ring Topology

In Ring topology the nodes are exactly connected to two or more nodes, forming a single continuous path for the transmission. If any of the nodes are damaged, then the whole network fails.

It is rare as it is expensive, difficult to install and manage.

49. Explain Mesh Topology

Mesh topology is a network topology in which all the nodes are connected respectively to the other nodes. Mesh topology is categorized into two parts:

Fully connected mesh topology and Partially connected mesh topology. Setup cost of mesh topology is high.

50. Explain Tree Topology

Tree topology is a combination of star and bus topologies. In this, all the star networks are connected to a single bus. Ethernet protocol is used in this topology. Tree topology depends primarily on the
\nmain bus and if it breaks, then the whole network gets damaged.

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