Networking Interview Questions and Answers

Q1. Define Network?
Network in general terms means a group of devices, connected with the help of some media in order to share some resources from a source to a destination and networking is a process of sharing the resources.

Q2. What Is A Node And Links?
In a network the devices at different endpoint located at a different location are called nodes and the physical communication medium they using is called links.

Q3. What is a Link?
Link is a physical or a logical component of a network to interconnect nodes or devices.

Q4. What is a router? Or define the basic requirements of a router?
A router is a layer 3 network device used to establish communication between different networks. Basic roles performed by a router are:

• Inter-network communication
• Best path selection
• Packet forwarding
• Packet filtering

Q5. What is a node?
Node is a connection point on network for data transmission. It can be a computer or printer or any type of device that is capable of sending and receiving the data over the network.

Q6. What Are The Layers Of The Osi Reference Model?
There are 7 OSI layers:
1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer

Q7. What is a gateway?
Gateway is a node of a network which can be used as an entrance for other network. It is a piece of hardware and different from default gateway.

Q8. What is the use of routing? or Why we use routing?
By default, a router provides inter-network communication only for directly connected networks. To establish communication between indirectly connected networks, we require ROUTING. We can use static or dynamic (IGP or EGP) routing, according to topology requirement.

Q9. What is point-point link?
A connection between two nodes of the network is referred as point to point network and that link which connects both nodes is point to point link.

Q10. Describe Domain Name System
There are two types of client/server programs:
1. First is used directly by the user, such as e­mail
2. Second supports other application programs
The Domain Name System (DNS) is a supporting program that is used by other programs such as to find the IP address of an e­mail recipient.

Q11. What is Multiple Access?
Multiple Access allows more than one devices to transmit data at the same time span. Star or Mesh topology can be used for this.

Q12. Define the criteria for best path selection of a router?
A router’s routing table contains only best route. To select a route as best, a router considers the following parameters;

• Longest prefix match
• Minimum AD (administrative distance)
• Lowest metric value

If all listed parameters are the same, then it would perform equal cost load balancing.

Q13. What’s the benefit of subnetting?
With the help of subnetting we can break a large network into smaller networks and assign IP addresses to those networks without changing our major network. It helps in utilizing our IP addresses more efficiently.

Q14. What Are The Difference Between Domain And Work Group?
Difference between domain and workgroup as follows:

Q15. What is BGP (Border Gateway Protocol)?
BGP is an exterior gateway protocol used to connect two or more different autonomous systems. It is widely being used to route the traffic of Internet. It can also work for internal AS but we have better protocols for internal connectivity. It has Administrative distance of 20 for external routes and 200 for internal routes

.Q16. Define “stuck in active.”
If a successor route (best route) fails, then the router sends a query message to its neighbor demanding a feasible successor (back-up route) and a query received by the router may be forwarded to other neighbors that could lead to a loop, as well. The wait for the response of query message is called “stuck in active” (SIA).

Q17. What is Gateway-to-Gateway protocol?
Gateway-to-Gateway protocol is now obsolete. This was being used for routing datagrams between internet gateways. It uses Minimum hop Algorithm.

Q18. Define Fully Qualified Domain Name And Partially Qualified Domain Name
In hierarchical namespace, names are defined in an inverted­tree structure with the root at the top. The tree can have only 128 levels: level 0 (root) to level 127. Each node in the tree has a label, which is a string with a maximum of 63 characters. The root label is a null string (empty string). In this tree, all the labels have a different name, which guarantee the uniqueness of the domain names. A full domain name is a sequence of labels separated by dots (.). The domain names are always read from the node up to the root.
1. Fully Qualified Domain Name :If a label is terminated by a null string or empty string, it is called a fully qualified domain name (FQDN).
2. Partially Qualified Domain Name : If a label is not terminated by a null string, it is called a partially qualified domain name (PQDN). A PQDN starts from a node, but it does not end with the root.

Q19. What is a Multi-homed Host?
Multi-homed host is defined as a node connected with more than one networks. Like a PC can be connected with both Home network and a VPN. These kind of hosts can be assigned with multiple addresses, one for each network.

Q20. Can we use OSPF without backbone area?
Yes, but it will be limited to intra-area (same area) communication. By default, Inter-area communication is not possible without backbone area.