Computer Networking Question & Answers | Part- 1

Networking Questions & Answers |Part-1

I think to provide some Q&A session for self practice. This can be referred when ever is required. This QA has been collected from different part of internet just to keep them at once place in the blog. I may not cover all the data around world. 

HA HA...

I am going to publish as part wise like part-1, part-2 etc. 

These are not any exam dumps. These may not help you to clear the CCNA or any relevant networking exams. This is just for your understanding and brainstorming.

The basic question always starts from router and switch roles, OSI layers etc.

So, 

1) What are the OSI Layer and name those layers.

A: OSI layer known as Open Systems Interconnection and was created by ISO (International Organization of Standardization). There are 7 layers in OSI layer such as;

• Application layer
• Presentation layer
• Session layer
• Transport layer
• Network layer
• Data link layer
• Physical layer

2) What is use of Flow Control?

A: The flow control provides a means for the receiver to govern the amount of data transmitted by the sender.

3) What is an IP address?

An Internet Protocol (IP) address is a numerical label that is assigned to devices participating in a computer network utilizing the Internet. It is a 32-bit number that identifies each sender or receiver of information that is sent in packets across the LAN /Internet. It has two parts: the identifier of a particular network on the Internet and an identifier of the particular device (which can be a server or a workstation) within that network. 

4) What is a subnet mask?

A subnet mask allows you to identify which part of an IP address is reserved for the network, and which part is available for host use. If you look at the IP address  alone, especially now with classless inter-domain routing, you can’t tell which part of the address is which. Adding the subnet mask, or net mask, gives you all the information you need to calculate network and host portions of the address with ease. In summary, knowing the subnet mask can allow you to easily calculate whether IP addresses are on. Subnetting enables the network administrator to further divide the host part of the address into two or more subnets.

5) What is ARP?

Short for Address Resolution Protocol, a network layer protocol used to convert an IP address into a physical address (called a DLC address), such as an Ethernet address. A host wishing to obtain a physical address broadcasts an ARP request onto the TCP/IP network. The host on the network that has the IP address in the request then replies with its physical hardware address. ARP is a very important part of IP networking. ARP is used  to connect OSI Layer 3 (Network) to OSI Layer 2 (Data- Link). For most of us, that means that ARP is used to link our IP addressing to our Ethernet addressing (MAC Addressing). For you to communicate with any device on your network, you must have the Ethernet MAC address for that device. If the device is not on your LAN, you go through your default gateway (your router). In this case, your router will be the destination MAC address that your PC will communicate with.

6) What is a default gateway? What happens if I don’t have one?

A default gateway is used by a host when an IP packet’s destination address belongs to someplace outside the local subnet. The default gateway address is usually an interface belonging to the LAN‘s border router.

In computer networking, a default network gateway is the device that passes traffic from the local subnet to devices on other subnets. The default gateway often connects a local network to the Internet, although internal gateways for connecting two local networks also exist.

7) What is a subnet?

A portion of a network which shares a network address in which each component is identified by a subnet number.

A subnet is a logical organization of network address ranges used to separate hosts and network devices from each other to serve a design purpose.

In many cases, subnets are created to serve as physical or geographical separations similar to those found between rooms, floors, buildings, or cities.

8) What is CIDR?

CIDR (Classless Inter-Domain Routing, sometimes known as super netting) is a way to allocate and specify the Internet addresses used in inter-domain routing more flexibly than with the original system of Internet Protocol (IP) address classes. As a result, the number of available Internet addresses has been greatly increased.

9) What is DHCP? What are the benefits and drawbacks of using it?

Benefits:

1. DHCP minimizes configuration errors caused by manual IP address configuration.

2. Reduced network administration.

Disadvantage

Your machine name does not change when you get a new IP address. The DNS (Domain Name System) name is associated with your IP address and therefore does change. This only presents a problem if other clients try to access your machine by its DNS name.

10) What are router interfaces? What types can they be?

Routers can have many different types of connectors; from Ethernet, Fast Ethernet, and Token Ring to Serial and ISDN ports.  Some of the available configurable items are logical addresses (IP,IPX), media types, bandwidth, and administrative commands. Interfaces are configured in interface mode which you get to from global configuration mode after logging in. The media type is Ethernet, Fast-Ethernet, Gigabit-Ethernet, Serial, Token-ring, or other media types. You must keep in mind that a 10Mb Ethernet interface is the only kind of Ethernet interface called Ethernet. A 100Mb Ethernet interface is called a Fast-Ethernet interface and a 1000Mb Ethernet interface is called a Gigabit-Ethernet interface.

11) How do I monitor IPSec?

To test the IPSec policies, use IPSec Monitor. IPSec Monitor (Ipsecmon.exe) provides information about which IPSec policy is active and whether a secure channel between computers is established.

12) How do I look at the open ports on my machine?

Windows: Open a command prompt (Start button -> Run-> type

“cmd”), and type:

netstat -a

Linux: Open an SSH session and type:

netstat -an

13) What protocol PPP uses to identify the Network layer Protocol?

A. NCP

B. ISDN

C.HDLC

D. LCP

A: NCP (Network Control Protocol)

14) What PPP protocol provides for dynamic addressing, authentication and multilink?

A. NCP

B. HDLC

C. LCP

D. X.25

A: LCP (Link Control Protocol)

15) What are two main types of ACL (access control list)?

A. Standard

B. IEEE

C. Extended

D. Specialized

A: Standard and Extended are used to configure security on a router. 

16) Which of the following protocol uses both TCP and UDP?

A. FTP

B. SMTP

C. Telnet

D. DNS

A: DNS

Remaining QA will be posted later post. 

-DR