Networking

Question 1

Protocols

Answer 1

How computers communicate with each other despite the different hardware and software.

Protocols have a specific purpose: exchanging emails, files, establishing communication, etc.

Question 2

Primary Goal of Networking

Answer 2

To exchange information between networked computers.

Question 3

Packets

Answer 3

Nothing but streams of bits running as electric signals (0’s & 1’s) on physical media used for data transmission. Such media can be a wire in a LAN or the air in a WiFi network.

Question 4

Whats the structure of a packet?

Answer 4

Header & Payload

Question 5

Header

Answer 5

Protocol specific structure: this ensures that the receiving host can correctly interpret the payload and handle the overall communication.

Question 6

Payload

Answer 6

The actual information (ie.data). It could be something like part of an email message or the content of a file during a download.

Question 7

How do the OSI Layers work?

Answer 7

They work on top of one another and every layer has its own protocol. Each layer serves the one above it.

The application layer does not need to know how to identify a process on a host, how to reach it and how to use the copper wire to establish a communication.

Question 8

ISO

Answer 8

International Organization for Standardization

Was never implemented but it is widely used in literature or when talking about IT networks.

Question 9

OSI

Answer 9

Open System Interconnection

Was never implemented but it is widely used in literature or when talking about IT networks.

Question 10

How do protocols work together? If every protocol has a header and a payload, how can a protocol use the one on its lower layer?

Answer 10

The idea is simple. The entire upper protocol packet (header plus payload) is the payload of the lower one; this is called encapsulation.

Question 11

What protocol stack is used on the internet?

Answer 11

TCP/IP

Question 12

TCP/IP has What 4 Layers?

Answer 12

Application
Transport
Network
Data Link

Question 13

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Answer 13

Screen Shot 2020-12-25 at 8.16.10 PM

Question 14

During encapsulation, every protocol adds?

Answer 14

Adds its own header to the packet, treating it as a payload. This happens to every packet sent by a host.

The receiving host does the same operation in REVERSE ORDER.

Question 15

In the TCP/IP layers, which layer encapsulates the Application layer?

Answer 15

The Transport Layer.

Question 16

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Answer 16

Screen Shot 2020-12-25 at 8.33.09 PM

Question 17

What are IP packets called?

Answer 17

Datagrams.

Question 18

What does the internet use to deliver packets?

Answer 18

IP (Internet Protocol)

Question 19

What is the IP?

Answer 19

The Internet Protocol runs on the internet layer of the Internet Protocol suite, also known as TCP/IP.

Question 20

IPv4 Address

Answer 20

Consists of 4 bytes, or octets; a byte consists of 8 bits.

Question 21

From a TCP/IP stack perspective, do the layers encapsulate upward or downward?

Answer 21

Downward (Application -> Transport -> Network -> Data Link

The application layer doesn’t need to know how to transport because the app layer headers and payload are within the transport layer and continues as such.