Computer Networks Interview Questions Set 1
Q.1. What is a Network?
Answer:- A network is a set of devices connected to each other using a physical transmission medium. In a network, nodes are used to connect two or more networks. E.g. Internet
Q.2. Differentiate between a router, a hub, and a switch.
| Hub |
Switch |
Router |
| Connects two or more Ethernet devices |
Connects two or more LAN devices |
Can connect devices or a LAN and WAN |
| Does not perform filtering |
Filters packets before forwarding them |
Highly configured to filter and send packets |
| Least intelligent, least expensive and least complex |
Similar to a hub, but more effective |
Extremely smart and complex
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Q.3. What is the OSI reference model?
Answer:- Open System Interconnection, the name itself suggests that it is a reference model that defines how applications can communicate with each other over a networking system. It also helps to understand the relationship between networks and defines the process of communication in a network.
Q.4. What are the layers in OSI Reference Models? Describe each layer.
| Physical Layer |
Converts data bit into an electrical impulse. |
| Data link Layer |
Data packet will be encoded and decoded into bits. |
| Network Layer |
Transfer of data grams from one to another. |
| Transport Layer |
Responsible for Data transfer from one to another. |
| Session Layer |
Manage and control signals between computers. |
| Presentation Layer |
Transform data into application layer format. |
| Application Layer |
An end user will interact with the Application layer. |
Q.5. What does a backbone network mean?
Answer:- In any system, backbone is the most principle component that supports all other components. Similarly, in networking, a Backbone Network is a Network that interconnects various parts of the network to which it belongs and has a high capacity connectivity infrastructure.
Q.6. What is Network Topology
Answer:- The physical layout of the computer network is called as Network Topology. It gives the design of how all the devices are connected in a network.
| Type |
Description |
| Bus Topology |
All the devices share a common communication line |
| Star Topology |
All nodes are connected to a central hub device |
| Ring Topology |
Each node connects to exactly two other nodes |
| Mesh Topology |
Each node is connected to one or more nodes |
| Tree Topology (Hierarchical Topology) |
Similar to star topology and inherits the bus topology |
| Daisy Chain Topology |
All nodes are connected linearly |
| Hybrid Topology |
Nodes are connected in more than one topology styles |
| Point-to-Point Topology |
Connects two hosts such as computers, servers, etc |
Q.7. Explain TCP/IP Model
Answer:- The most widely used and available protocol is TCP/IP i.e. Transmission Control Protocol and Internet Protocol. TCP/IP specifies how data should be packaged, transmitted and routed in their end to end data communication. There are four layers described below:
- Application Layer: This is the top layer in the TCP/IP model. It includes processes that use Transport Layer Protocol to transmit the data to their destination. There are different Application Layer Protocols such as HTTP, FTP, SMTP, SNMP protocols, etc.
- Transport Layer: It receives the data from the Application Layer which is above the Transport Layer. It acts as a backbone between the host's system connected with each other and it mainly concerns about the transmission of data. TCP and UDP are mainly used as Transport Layer protocols.
- Network or Internet Layer: This layer sends the packets across the network. Packets mainly contain source & destination IP addresses and actual data to be transmitted.
- Network Interface Layer: It is the lowest layer of the TCP/IP model. It transfers the packets between different hosts. It includes encapsulation of IP packets into frames, mapping IP addresses to physical hardware devices, etc.
Q.8. What are differences between TCP and UDP?
Answer:-
| TCP |
UDP |
| TCP stands for Transmission Control Protocol |
UDP is stands for User Datagram Protocol or Universal Datagram Protocol |
| Once the connection is setup, data can be sent bi-directional i.e. TCP is a connection oriented protocol |
UDP is connection less, simple protocol. Using UDP, messages are sent as packets |
| The speed of TCP is slower than UDP |
UDP is faster compared to TCP |
| TCP is used for the application where time is not critical part of data transmission |
UDP is suitable for the applications which require fast transmission of data and time is crucial in this case. |
| TCP transmission occurs in a sequential manner |
UDP transmission also occurs in a sequential manner but it does not maintain the same sequence when it reaches the destination |
| TCP tracks the data sent to ensure no data loss during data transmission |
UDP does not ensure whether receiver receives packets are not. If packets are misses then they are just lost |
Q.9. What are similarities between TCP and UDP?
Answer:- Common factors in TCP and UDP:
- TCP and UDP are the most widely used protocols that are built on the top of IP protocol.
- Both protocols TCP and UDP are used to send bits of data over the internet, which is also known as ‘packets’.
- When packets are transferred using either TCP or UDP, it is sent to an IP address. These packets are traversed through routers to the destination.
Q.10. What is HTTP and what port does it use?
Answer:- HTTP is HyperText Transfer Protocol and it is responsible for web content. Many web pages are using HTTP to transmit the web content and allow the display and navigation of HyperText. It is the primary protocol and port used here is TCP port 80.
Q.11. What is HTTPs and what port does it use?
Answer:- HTTPS is a Secure HTTP. HTTPS is used for secure communication over a computer network. HTTPS provides authentication of websites that prevents unwanted attacks. In bi-directional communication, HTTPS protocol encrypts the communication so that the tampering of the data gets avoided. With the help of an SSL certificate, it verifies if the requested server connection is a valid connection or not. HTTPS uses TCP with port 443.
Q.12. What is a Proxy Server and how do they protect the computer network?
Answer:- For data transmission, IP addresses are required and even DNS uses IP addresses to route to the correct website. It means without the knowledge of correct and actual IP addresses it is not possible to identify the physical location of the network.
Proxy Servers prevent external users who are unauthorized to access such IP addresses of the internal network. The Proxy Server makes the computer network virtually invisible to the external users.
Q.13. What are different ways of securing a computer network?
Answer:- There are several ways to do this. Install reliable and updated anti-virus program on all computers. Make sure firewalls are setup and configured properly. User authentication will also help a lot. All of these combined would make a highly secured network.
Q.14. What is NIC?
Answer:- NIC stands for Network Interface Card. It is also known as Network Adapter or Ethernet Card. It is in the form of an add-in card and is installed on a computer so that the computer can be connected to a network. Each NIC has a MAC address which helps in identifying the computer on a network.
Q.15. What is the function of the OSI Session Layer?
Answer:- This layer provides the protocols and means for two devices on the network to communicate with each other by holding a session. This includes setting up the session, managing information exchange during the session, and tear-down process upon termination of the session.
Q.16. What is the difference between the Internet, Intranet, and Extranet?
Answer:- The terminologies Internet, Intranet, and Extranet are used to define how the applications in the network can be accessed. They use similar TCP/IP technology but differ in terms of access levels for each user inside the network and outside the network.
Internet: Applications are accessed by anyone from any location using the web.
Intranet: It allows limited access to users in the same organization.
Extranet: External users are allowed or provided with access to use the network application of the organization.
Q.17. What is NOS?
Answer:- NOS, or Network Operating System, is specialized software whose main task is to provide network connectivity to a computer in order for it to be able to communicate with other computers and connected devices.
Q.18. What are ipconfig and ifconfig?
Answer:- Ipconfig stands for Internet Protocol Configuration and this command is used on Microsoft Windows to view and configure the network interface. The command ipconfig is useful for displaying all TCP/IP network summary information currently available on a network. It also helps to modify the DHCP protocol and DNS setting.
Ifconfig (Interface Configuration) is a command that is used on Linux, Mac, and UNIX operating systems. It is used to configure, control the TCP/IP network interface parameters from CLI i.e. Command Line Interface. It allows you to see the IP addresses of these network interfaces.
Q.19. What is DoS?
Answer:- DoS, or Denial-of-Service attack, is an attempt to prevent users from being able to access the internet or any other network services. Such attacks may come in different forms and are done by a group of perpetuators. One common method of doing this is to overload the system server so it cannot anymore process legitimate traffic and will be forced to reset.
Q.20. Differentiate Communication and Transmission?
Answer:- Through Transmission the data gets transferred from source to destination (Only one way). It is treated as the physical movement of data.
Communication means the process of sending and receiving data between two media (data is transferred between source and destination in both ways).
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