Networking

Question 1

What are the layers of the OSI model

Answer 1

Open System Interconnection is a model which describes how different applications communicate on a network.
1 - Physical: Media, Signal and Binary transmission
2 - Data Link: MAC and LLC (Physical addressing)
3 - Networking: Routing and IP (Logical addressing)
4 - Transport: End to End connections and reliability
5 - Session: Interhost communication
6 - Presentation: Data representation and Encryption
7 - Application: Network Process to Application

Question 2

What is the TCP/IP Model

Answer 2

Transmission Control Protocol

- Describes how data gets transmitted and routed from end to end communication

Question 3

What are the layers of the TCP/IP Model

Answer 3

1. Network Access Layer
2. Internet Layer
3. Transport Layer
4. Application Layer

Question 4

What is difference between TCP and UDP

Answer 4

• TCP is connection oriented and UDP is connectionless
• TCP is ordered vs unordered
• TCP is reliable vs unreliable
• TCP is slower
• TCP does error recovery
• TCP uses a handshake

Question 5

What is the TCP handshake process

Answer 5

• 3 Way handshake
  1. Client sends a SYN-SEND (contains a seq #) to Server
  2. Server receives SYN and sends SYN-RECEIVED back to Client
  3. Client sends ACK to Server
  4 ESTABLISHED

Question 6

What is a firewall?

Answer 6

A concept of a security system that protects computers from unauthorized access or cyber attack

Question 7

What do you mean by DNS?

Answer 7

DNS Stands for Domain Name System. It’s an internet address mapping process with the local name. We can also call it as an internet phonebook.

Question 8

What are the IP classes

Answer 8

Class A: 1-127.x.x.x, Netmask 255.0.0.0
Class B: 128-191.x.x.x, Netmask 255.255..0.0
Class C: 192-223.x.x.x, Netmask 255.255.255.0
Class D: 224-239.x.x.x, reserved for multicasting
Class E: 240-255, Reserved for experimental purposes.

Question 9

What are the 3 network modes

Answer 9

• simplex: send info in one direction
• half duplex: send data in both directions, but not in parallel
• full duplex: send data in both directions in parallel

Question 10

What is a proxy server

Answer 10

Proxy servers prevent external users who are unauthorized to access such IP addresses of the internal network. It makes the computer network virtually invisible to external users.

Question 11

What is DHCP

Answer 11

Dynamic Host Configuration Protocol

- Automatically assigns IP addresses to network devices

Question 12

What is SNMP

Answer 12

SNMP stands for Simple Network Management Protocol. It is a network protocol used for collecting organizing and exchanging information between network devices.

Question 13

Why is the OSI Model standard termed 802.xx?

Answer 13

The OSI model was started in the month of February in 1980. So it is standardized as 802.XX. This ‘80’ stands for the year 1980 and ‘2’ represents the month of February.

Question 14

How is a network certified as an effective Network?

Answer 14

• Performance
• Reliability
• Security

Question 15

Explain Data Encapsulation

Answer 15

Encapsulation means adding one thing on top of the other thing. When a message or a packet is passed through the communication network (OSI layers), every layer adds its header information to the actual packet.

Question 16

Name some network topologies

Answer 16

1 - Bus
2 - Star (most common)
3 - Ring

Question 17

Name some network troubleshooting commands

Answer 17

netstat
ping
traceroute (hops)
ifconfig/ipconfig
ip addr show

Question 18

A TCP connection on a network can be uniquely defined by 4 things

Answer 18

source IP, source port, destination IP, and destination port

Question 19

How do you ping a port on a server?

Answer 19

telnet

nmap

Question 20

How do you create a DHCP reservation

Answer 20

You need the MAC address

Question 21

What is LDAP

Answer 21

Lightweight Directory Access Protocol

To look up for the information from the server, e-mail and another program follows or uses the internet protocol.