IPv4 Addresses
IP addresses develop by IETF (Internet Engineering Task
Force).
IP is network layer routed protocol, which are use for
numeric identification of a device on TCP/IP network.
- Binary numeric system: represent data in bits 0 or 1
- Decimal numeric system: represent data in digits, 0-9
- Hexa decimal numeric system: represent data in 0-9 and A-F
Mac address is a hexa decimal format, which consist of 12 hexa
(48 bits). 1 Hexa=4bits. Authorized by IEEE (Institute of Electrical Electronic
Engineering).
- First 6 hexa of Mac address called OUI (Organization Unique Identifier), we can’t change it
- Second 6 hexa of Mac address called vender assign numbers
We have five classes
of IP addresses: A, B, C, D, E
Class A: Range (0-127). Rule: first bit of first byte must be off, at
least one bit from the remaining must be on. Ex: 01000000.
Total network and host in class A:
2n-1, where n=number of network bits. 28-1 -2=27-2=126
(networks).
2P-2, where p=number of
host bits. 224 -2=16777214 (hosts).
Class B: Range (128-191). Rule: first bit of first byte must be
on second bit of first byte must be off, remaining bits may be on or off. Ex:
10111001.
Total network and host in class B:
2n-2, where n=number of network bits. 216-2=214 =16384
(networks).
2P-2, where p=number of
host bits. 216-2=65534 (hosts).
Class C: Range (192-223). Rule: first bit of first byte must be
on second bit of first byte must be on third bit of first byte must be off, at
least the remaining bits may be on or off. Ex: 11010000.
Total network and host in class C:
2n-3, where n=number of network bits. 224-3=221=2097152
(networks).
2P-2, where p=number of
host bits. 28-2=254 (hosts).
Class D: Range (224-239). Use for multicasting, no network and host
portion.
Class E: Range (240-255). Reserved for IETF, use for research
purposes. No network and no host portion.
Subnet mask: Define the network and host portion, in subnet mask on
bits are called network portion and off bits are called host portion.
Ex: 192.168.1.0 255.255.255.0/24
CIDR: (Classless inter domain
routing) or Prefix, /24.
Private and Public IPs
Private IPs: 192.168.0.0-192.168.255.255,
172.16.0.0-172.31.255.255, 10.0.0.0-10.255.255.255. Except these IPs all IPs
are called Public IPs.
Understanding the power of 2: Power of 2 is important to
understand and memorize for use with IP subnetting.
21=2, 22=4, 23=8, 24=16,
25=32, 26=64, 27=128, 28=256, 29=512,
210=1024, 211=2048, 212=4096, 213=8192,
214=16384 etc.
