IP Addressing

An IP addressing is a numeric identifier assigned to each machine on an IP Network. Its IP address is a software address, not a hardware address.

 Bit= A bit is one digit, either a 1 or a O

Byte= A byte is 7 or 8 bit, but always assume a byte is 8 bit

Octet=an octet made up of 8 bits (binary).

Network address=Routing to send packet to a remote network (10.0.0.0 or 172.16.0.0 or 192.168.10.0)

Broadcast address=application and host to send info to all host. (255.255.255.255 or 172.16-31.255.255)

APIPA=It is the minimum information needed for hosts to communicate when a DHCP server not available. (IP: 169.254.0-2555.1-254 also subnet mask of 255.255.0.0 default class B).

IP addressing classes of Network

Class A: Network>>Host>>Host >> Host (IP: 1-126.22.102.70/8 or subnet mask 255.0.0.0)

 This section first bit reserving & 1^st byte long. (00000000=0 & 01111111=127) 7 bits all OFF & then turn all ONE. Class A define 0 & 127 is designate default route & diagnostic address. Only use 1 to 126 ranges IP. A network address is 128 minus 2 & First 1 byte Network assigned and last 3 bytes remaining hosting address. Class A address has 3 bytes (24 bit positions) for the host address of a machine. This means there is 2²⁴-value 16,777,216 this is potential unique host address for each class A Network.

Class B: Network >>Network>>Host>>Host (IP: 128-191.22.102.70/16 or subnet mask 255.255.0.0)

This class section first 2 bytes are assigned to the network address and the remaining 2 bytes are used for host address. (10000000=128 & 10111111=191) RFC state that the first bit of the first byte always is turned ON but the second bit must always be turned OFF. Class B networking address being 2 bytes (8 bits positions), This leaves 14 bit positions available to manipulate, so we get 2¹⁴-value 16,384 unique potential host address for each class B Network.

Class C: Network>>Network>>Network>>Host (IP: 192-223.22.102.70/24 or subnet mask 255.255.255.0)

This section first 3 bytes network address are dedicated to the network portion of the address only 1 measly byte remaining for the host address. (11000000=192 & 11011111=223) RFC state that the first 2 bit of the first byte always is turned ON but the Third bit must always be turned OFF. This section 3 bytes, or 24 bits, minus 3 reserved positions leaves 21 positions. There are 221 value 2,097,152 unique potential host address for each class C network.

Class D: Multicast ( IP: 224-239.255.255.255 all no hosting address all network address )

Class E: Research (IP: 240-255.0.0.0 for scientific purpose use only)

Private IP Address

The people who created the IP addressing scheme also created what we call private IP address. They are not routable through the internet.

Reserved IP address space

Address class	Reserved address space
Class A	10.0.0.0 through 10.255.255.255
Class B	172.16.0.0 through 172.31.255.255
Class C	192.168.0.0 through 192.168.255.255

Reserved IP addresses (continued)

Address                                                           Function

Host address of all 0s                                      Interpreted to mean “network address” or any host on

specified network.

Host address of all 1s                                      Interpreted to mean “all hosts” on the specified network;

for example, 128.2.255.255 means “all hosts” on

network 128.2 (Class B address).

Entire IP address set to all 0s                         Used by Cisco routers to designate the default route.

Could also mean “any network.”

Entire IP address set to all 1s                         (same as 255.255.255.255)

Broadcast to all hosts on the current network; sometimes called an “all 1s broadcast” or limited broadcast.