IP Address and Subnetting

• IP version 4 (IPv4)


  32-bit (4 bytes) addressing scheme
• IP version 6 (IPv6)


  128-bit (16 bytes) addressing scheme
• MAC (Media Access Control) address


  Unique physical address of computers, assigned by manufacturer
• Organizational Unique Identifier (OUI)


  First 24 bits of MAC address that identifies the manufacturer
• Vendor-Assigned


  Remaining 24 bits of MAC address that uniquely identifies the individual device
• IP address


  Address assigned to uniquely identify each device on an IP network

  
• Public IP address


  Used by computers to find each other online and exchange information, assigned by ISP

  
• Static public IP address


  Fixed IP address used for hosting web pages or services

  
• Dynamic public IP address


  IP address chosen from a pool that changes each time connected to the internet
• Private IP address


  Used by computers on a network to communicate with the router, can change each time connected
• Network ID/field


  Identifies the host located on the same physical network
• Host ID (host address)


  Identifies the individual host (workstation, server, router, etc.) within a network
• Class A address


  • Uses only the first octet (8 bits) of the 32-bit number to indicate the network address, remaining 24 bits for host addresses
  • Network range: 1.0.0.0 to 127.0.0.0
  • Maximum hosts per network: 16,777,214
• Class B address


  • Uses two octets (16 bits) to indicate the network address, remaining 16 bits for host addresses
  • Network range: 128.0.0.0 to 191.255.255.255
  • Maximum hosts per network: 65,534
• Class C address


  • Uses the first three octets (24 bits) to identify the network portion, remaining 8 bits for host addresses
  • Network range: 192.0.0.0 to 233.255.255.255
  • Maximum hosts per network: 254
• Class D address


  • Used for multicasting, first 4 bits are 1110, range: 224.0.0.0 to 239.255.255.255
• Class E address


  • Reserved by IETF for research, first 4 bits are 1111, range: 240.0.0.0 to 255.255.255.255
• Subnet mask (default mask)


  Determines which portion of an IP address identifies the network and which portion identifies the host
• Default Gateway


  Address of the nearest routing device used by the host to forward packets onto the network
• IANA IPv4 Special-Purpose Addresses

  • Diagnostic (Loopback/Localhost Address): 127.0.0.0 - 127.255.255.255
  • Default Network: 0.0.0.0
  • Network Broadcast: 255.255.255.255
  • Private-use of Internet Space: 10.0.0.0 - 10.254.254.254, 172.16.0.0 - 172.16.254.254, 192.168.0.0 - 192.168.254.254
  • Link-Local Addresses: 169.254.0.0 - 169.254.254.254

  
• Decimal to Binary

  1. Divide decimal number by 2 and note remainder

  2. Divide quotient by 2 and note remainder

  3. Repeat until quotient is 0

  4. Write remainders in reverse order

  5. Write the remainders in such a way that the last remainder is written first, followed by the rest in the reverse order.

  6. LSB and MSB
• The IP address 117.149.29.2 is the dotted-decimal equivalent of the binary 01110101.10010101.00011101.00000010

  
• Subnet Masking

  1. Convert IPv4 address from decimal to binary

  2. AND the binary IP address with the default subnet mask

  
• Least Significant Bit (LSB)


  The binary number is at the top
• Most Significant Bit (MSB)


  The binary number is at the bottom
• F = xy


  Boolean function
• Diagnostic (Loopback/Localhost Address)


  It is used for testing and debugging of programs, hardware, protocol, and connections. (SYN-ACK)
• Default Network


  It is used for routing internet datagram (TCP).
• Network Broadcast


  It is used for broadcasting messages to the entire network.
• Private-use of Internet Space


  It is the preconfigured default IP addresses for network devices to extend IPv4 spaces (Home, Commercial, Enterprise)
• Link-Local Addresses


  If DHCP is not present, these IP addresses will be selected and configured by the network device.
• Private-use of Internet Space


  • 10.0.0.0 - 10.254.254.254
  • 172.16.0.0 - 172.16.254.254
  • 192.168.0.0 - 192.168.254.254
• Link-Local Addresses


  • 169.254.0.0 - 169.254.254.254
• Diagnostic (Loopback/Localhost Address)


  • 127.0.0.0 - 127.255.255.255
• Default Network


  • 0.0.0.0
  • 255.255.255.255