Section 2 : How Computer Networks Work

Question 1

What are Network Protocols?

Answer 1

• Computers communicate with each other using Network Protocols.
• Protocols are rules governing how machines exchange data and enable effective communication.
• Some everyday examples:
  
  • When you call somebody , you pickup the phone, ensure there is a dial tone, and if there is, you dial the number.
  • When you drive your car, you follow and obey the rules of the road
• Physical Protocols: describes the medium(wiring), the connections (RJ-45 port), and the signal(voltage leve on a wire)
• Logical Protocols: Software controll how and when data is sent and received to computers, supporting physical protocols.
• Computer networks depend on many different types of protocols in order to work properly.
• Example of common TCP/IP suite of Protocols:
  
  • Web communication: HTTP
  • Email: POP3, SMTP,IMAP
  • File Transfer: FTP

Question 2

What is the OSI Model?

Answer 2

The Open Systems Interconnection (OSI) Reference Model

• A conceptual framework showing us how data moves throughout a network.

Why was it developed?

• Create to give us a guide to understand how networks operate.

NB: It is only a reference model, amd it’s not implemented in the real world but TCP/IP is.

Question 3

What are the two categories fo the OSI Model Stack?

Answer 3

• Upper Layers (Host Layers)
  
  • Handled by the host computer and performs application-specific functions such as data formatting, encryption and connection management.
• Lower Layers(Media Layers)
  
  • Provide network-specific functions, such a routing ,addressing and flow control.

Question 4

What are the 7 Layers of the OSI Model?

Answer 4

• Application Layer (Data)
• Presentation Layer (Data)
• Session Layer (Data)
• Transport Layer (Segment)
• Network Layer (Packet)
• Data Link Layer (Frame)
• Physical Layer (Bit)

Question 5

What is the TCP/IP Model?

Answer 5

• The TCP/IP suite is the most common used protocol suite in the networking world
• It is essesntially the protocol suite in which the internet was built.
• It is the standard for computer networking
• it is based on a 4-Layer model that is similar to the OSI Model

Question 6

What are the 4 layers of the TCP/IP Model?

Answer 6

• Application Layer
• Transport Layer
• Network/Internet Layer
• Network Interface Layer

Question 7

What is a MAC Address?

Answer 7

• Media Access Control (MAC)
  
  • Physical address of the network adapter card
  • OSI Layer 2 (Data Link)
  • TCP/IP Layer 1(Network Interface)
• Six bytes (48 bits), usually represented hexadecimal
  
  • First three bytes(24 bits) are assigned by the IEEE to the manufactorer
    
    • OUI assigned by IEEE - Organizationally Unique Identifier (e.g. Dell, HP)
  • Last three bytes (24 bits) are usually assigned sequentially:
    
    • Allows for uniqueness; Duplications are rare.
  • 00:21:70:65:06:f3. or 00-21-70-6F-06-F2
  • 2²⁴ = ~16.7 Million addresses

Question 8

What are IPv4 Addresses?

Answer 8

• Internet protocol version 4
  
  • OSI Layer 3 (Nework)
  • Dotted Decimal Format masks Binary Format

NB:

8 bits = 1 byte = 1 octet

32 bits = 4 bytes

Question 9

Comparing IP and MAC Address?

Answer 9

IP Addresses:

• Network (OSI Layer 3) Addresses
• 32 bit address
• Logical Addresses
• Allow network-to-network communication via routers
• Dotted Decimnal Notation
  
  • 192.168.100.25

MAC Addresses:

• Data Link (OSI Layer 2) Addresses
• 48 bit address
• Physical Addresses
• Fixed, assigned by manufacturer
• Physically burned on NIC (network Interface Card)
• Allows internetwork communication via hubs, switches, and routers (Local LAN communication)

Question 10

Simplex VS Half Duplex VS Full Duplex Communication?

Answer 10

• Simplex (Radio station signal)
  
  • communation channel that sends infromation in one direction only.
• Half Duplex
  
  • Can send and receive data, but not at the same time.
• Full Duplex
  
  • Can send and receive data simultaneously.