TCP/IP protocol

• What does TCP/IP stand for?

  Transmission Control Protocol / Internet Protocol
• What is the primary purpose of TCP/IP?

  To enable communication between devices on the Internet
• What are the four layers of the TCP/IP stack?

  • Application
  • Transport
  • Network
  • Link
• What role does the application layer play in TCP/IP?

  Selects and uses the correct protocol
• How does the transport layer function in TCP/IP?

  Establishes a virtual path and splits transmission into packets
• What is contained in each packet sent by the transport layer?

  Sequence number and port number
• What does the sequence number in a packet indicate?

  It identifies a packet's position in the transmission
• What is the purpose of the network layer in TCP/IP?

  Provides correct IP addresses for packets
• How do routers function within the network layer?

  They use IP addresses to send packets to destinations

  
• What does the link layer control in TCP/IP?

  Physical connections between hardware in a network
• What are MAC addresses used for in TCP/IP?

  To identify hardware to which packets are sent
• How do MAC addresses change in a network?

  They change with every hop through the network
• What happens to a packet at the receiving end of TCP/IP?

  It is stripped of extra information by reversing the stack
• What does the link layer remove from a packet?

  MAC addresses
• What does the transport layer use to determine the correct application for a packet?

  The packet's port number
• What is formed when an IP address is combined with a port number?

  A socket address
• What is the purpose of a socket address?

  To identify the application for a packet
• What are some well-known ports and their purposes?

  • FTP: 20 & 21 (File transfer)
  • SSH: 22 (Remote management)
  • HTTP: 80 (Web page delivery)
  • HTTPS: 443 (Secure web page delivery)
  • POP3: 110 & 995 (Email retrieval)
  • SMTP: 25, 587 & 465 (Email sending)
• What is the purpose of FTP?

  Sending files between devices
• How can clients access FTP servers?

  Anonymously or non-anonymously
• What does SSH require for remote access?

  Username/password combination
• What does HTTPS do during transmission?

  Encrypts information to secure it
• What is the structure of an IP address?

  Network identifier and host identifier
• What is a subnet mask used for?

  To determine the network identifier of an IP address
• Given an IP address of 192.168.3.24 and a subnet mask of 255.255.255.0, what is the network identifier?

  192.168.3.0
• What happens when more bits are assigned to the network identifier?

  More different subnets can be created
• What are the two types of IP addresses in common use?

  • IPv4
  • IPv6
• How are IPv4 addresses structured?

  Four parts separated by dots
• Why was IPv6 created?

  Due to the shortage of IPv4 addresses
• How are IPv6 addresses structured?

  Eight blocks separated by colons
• How many bits do IPv6 addresses use?

  128 bits
• What is the difference between public and private IP addresses?

  Public are routable, private are not
• Why can't every device have a public IP address?

  There aren't enough public IP addresses available
• What happens to an IP address when a device leaves the network?

  It is returned to the pool for allocation
• What is Network Address Translation (NAT)?

  • Allows multiple devices to share a single public IP address
  • Translates private IP addresses to public IP addresses
  • Helps conserve the number of public IP addresses used
• Why is it important that the same IP address is never issued twice?

  To avoid network conflicts and ensure uniqueness
• Why is assigning each device its own private IP address not sensible?

  Devices may leave and never return
• What is the role of NAT in a network?

  NAT allows private IP addresses to communicate with the Internet
• What type of IP address does a router have on the private network side?

  Private IP address
• Why can't a server respond directly to a computer with a non-routable IP address?

  Because the IP address is not globally unique