NWF CHAP2

• IP address


  Unique "address" for every end device in a computer network
• Sending a message from one device to another

  1. Specify the recipient's address

  2. Deliver the message to the recipient
• Dotted decimal format


  IP addresses expressed as x.x.x.x, where x is an integer from 0 to 255
• IP addresses are 32-bit binary numbers
• Dotted decimal format


  Used to make IP addresses easier to read compared to binary format
• Converting IP address from binary to dotted decimal

  1. Divide 32-bit binary into 4 groups of 8 bits

  2. Convert each 8-bit group to decimal

  3. Insert dots between decimal values
• Each group of 8-bit binary can have values from 0 to 255 (inclusive)
• Network portion


  Part of IP address that represents a group of IP addresses
• Host portion


  Part of IP address that uniquely defines each IP address within a group
• Subnet mask


  32-bit binary number used to indicate the division between network and host portions of an IP address
• Deriving subnet mask


  1. Subnet mask consists of a string of '1's (network portion) followed by a string of '0's (host portion)

  2. Convert subnet mask from binary to dotted decimal format
• IP classes


  Different groups of IP addresses (A, B, C, D, E) defined by IANA
• Classes A, B, and C are assigned to governments, companies, schools, and public entities for use on the Internet
• Classes D and E are reserved for multicasting and experimentation
• IP class formats


  • Class A starts with '0', Class B starts with '10', Class C starts with '110', Class D starts with '1110', Class E starts with '11110'
• Class A network IDs range from 1 to 126, Class B network IDs range from 128.0 to 191.255, Class C network IDs range from 192.0 to 223.255.255
• Class A IP addresses

  ARIN reserves Class A IP addresses for governments throughout the world
• Class D IP addresses

  Reserved for multicasting
• Class E IP addresses


  Reserved for research, testing, and experimentation
• IP address classes


  • Class A starts with '0'
  • Class B starts with '10'
  • Class C starts with '110'
  • Class D starts with '1110'
  • Class E starts with '11110'
• IP address class ranges

  • Class A: 1 - 126
  • Class B: 128.0 - 191.255
  • Class C: 192.0 - 223.255.255
  • Class D: 224 - 239
  • Class E: 240 - 247
• Number of host addresses for IP classes

  2^n - 2, where n is the number of bits in the host portion
• Class A IP addresses are reserved for governments throughout the world
• Class B IP addresses are assigned to large- and medium-sized companies
• Class C IP addresses are assigned to groups that do not meet the qualifications to obtain Class A or B addresses
• Class D addresses are also known as "Multicast Addresses"
• The IANA reserves Class E addresses for research, testing, and experimentation
• IP address 166.74.105.106


  • Class B
• Classful IP addressing is wasteful as the standard subnet masks define the network portion as a multiple of 8-bits
• Classless Inter-Domain Routing (CIDR)


  Replaced the old process of assigning IP addresses based on Class A, B and C addresses, by breaking away from the restriction of using network portion of multiple of 8-bits
• Deriving subnet mask for a classless IP address

  1. Network portion represented by '1's

  2. Host portion represented by '0's

  3. m + n = 32 bits

  
• Subnet mask for IP address with network prefix /20

  • 255.255.240.0

  
• Subnet mask for IP address with network prefix /13

  • 255.248.0.0