Routing Interview Questions and Answers

Routing Interview Questions and Answers

Networking online training1. What is Routing?

Routing is the act of moving information across an internet work from a source to a destination. Routing is often contrasted with bridging, which might seem to accomplish precisely the same thing to the casual observer.

2. Description about Router?

ANS: A router is a device that forwards data packets across computer networks. Routers perform the data “traffic directing” functions on the Internet. A router is connected to two or more data lines from different networks. When data comes in on one of the lines, the router reads the address information in the packet to determine its ultimate destination.

3. What is Routing Protocol? Explain its purposes.

ANS: Routing protocol specifies how the routers communicate, disseminating the information which enables the routers to be selected between two nodes in a network.

Routing protocol interacts and informs the hardware that is needed to transmit the data between transmitter and the receiver for transmission over network.

4. How do routers populate routing entry for a directly connected network?

ANS: A directly connected network refers to the network address corresponding to the IP address and subnet mask configured on the specific network interface card on the router. The IP address and subnet mask would be “And” ed to derive the network address.

5. What is Path Determination?

ANS: A metric is a standard of measurement, such as path length, that is used by routing algorithms to determine the optimal path to a destination. To aid the process of path determination, routing algorithms initialize and maintain routing tables, which contain route information. Route information varies depending on the routing algorithm used.

6. What is Router? Explain components of Routers.

ANS: The way switches connect multiple computers, a router connects multiple networks. Routers comprise of data consisting of large tables of networks and addresses. Routers use algorithms to determine the shortest route to an address in a network.

7. What are the basic components of routers?

ANS: Components of Router

Internal components:

ROM:- Used to store the routers bootstrap details, operating system software.
Flash memory: – holds the operating systems images. The content is retained when the router is restarted.
RAM: – Used to store the Routing tables, configuration files, caching and buffering details. Content is lost when lost router is switched off or restarted.
NVRAM:- Stores the routers startup config files. Data is non volatile.
Network interfaces to connect router to network.

External components:

Virtual terminals: For accessing routers
Network management stations.

8. What is Switching?

ANS: Switching algorithms are relatively simple and are basically the same for most routing protocols. In most cases, a host determines that it must send a packet to another host. Having acquired a router’s address by some means, the source host sends a packet addressed specifically to a router’s physical (Media Access Control [MAC]-layer) address, this time with the protocol (network- layer) address of the destination host.

9. What is the Routing Engine Architecture?

ANS: The Routing Engine handles all the routing protocol processes as well as processes controlling interfaces, router components, system management, and user access. These processes run on top of a kernel that interacts with the Packet Forwarding Engine.

10. What is Routing table?

ANS: A routing table stores the routes of the various nodes in a network. Nodes can be any electronic device connected to the network. The table is usually stored in a router or the network computer as a database or file. This information helps to fond the best possible path. The routing table has at least 3 fields: the destination network id, cost of the path, next hop or address to send the packet.

11. What is Routing Protocols?

ANS: Routing protocols are used to assist in achieving the basic purpose of routing. They specify the routers the method to communicate with each other. They help the routers select the best possible path between nodes.

12. Types of Routing Protocols?

ANS: There are different types of protocols such as:

Link-state routing protocols,
Path vector protocols and
Distance vector routing protocols.

These protocols prevent routing loops to form or break if formed already. They help to decide preferred routes from a sequence of hop costs.

13. Can routers check Ethernet frames?

ANS: Routers look for information inside the IP packet header for routing the packets. But the packets itself would be encapsulated inside frames like ethernet, PPP etc. For example, if the IP packet is encapsulated inside an ethernet frame, the router would first need to check the destination mac-address inside the frame and verify if it is intended for itself and only then be able to process the IP packet header, which would be the data inside the packet.

14. How do routers forward IP packets?

ANS: When a router receives an IP packet, it would check the destination IP address in the packet. The router would then performing an “And “ operation with the subnet mask of the different route table entries with the destination IP address and verify if the corresponding network address in the routing table matches. On a match, the packet would be forwarded to the interface to which it the route entry is associated with.

15. Does a computer have routing tables?

ANS: A computer has routing table. The routing table is populated by the operating system, once the IP address, subnet mask and default gateway is configured. On a windows PC, the routing table can be viewed by typing the command ‘route print’ on the command prompt.

16. What type of IP address (Private or Public) is used when a computer is connected to the internet directly?

ANS: Public IP address

17. What is ARP?

ANS: ARP, the ADDRESS RESOLUTION PROTOCOL. ARP is the protocol which converts the IP address to an address appropriate to the hardware type (ie, Ethernet addresses on an ether network). After normal routing protocols have done their work, ARP springs in to action. It’s what actually gets packets from one machine to another.

18. On which hardware component on a computer is the IP address configured?

ANS: The IP address is configured on the network card.

19. What is ifconfig?

ANS:  “ifconfig” is a command found in most *NIX operating systems (think UNIX, Linux, BSD, etc…). It’s equivalent in Windows is “ipconfig”.

It is a command you call from the shell (not the graphical user interface) that allows you see/set IP configurations for a specific interface.

20. What is Default gateway?

ANS: In computer networking, a gateway is a node (a router) on a TCP/IP network that serves as an access point to another network. A default gateway is the node on the computer network that the network software uses when an IP address does not match any other routes in the routing table.

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