Posts Tagged ‘address’
July 22nd, 2008 | 
Author: ANDing: (Boolean and)
Computers use digital logic to interpret IP addresses
This logic is called a Boolean AND. It is the comparison of two bits to yield:
1 & 1 = 1
1 & 0 = 0
0 & 1 = 0
0 & 0 = 0
Any # ANDed with 0 is always 0
Any # ANDed with 1 is always the original #
The ANDing of an IP address & mask = network address
A subnet mask “masks” the host bits of an IP address
Routers and hosts use ANDing to determine networks
It is frequently necessary to be able to use ANDing
You will need to know how routers make routing decisions
Start with the IP address & mask above/below each other
10101100.00010000.00010100.00100011 172.16.24.35 (Host)
11111111.11111111.11111111.111 00000 255.255.255.224
——————————————————
10101100.00010000.00010100.00100000 172.16.23.32 (network address for
host /27)
Tags: vlan, ip, wan, cisco, study, switch
IP Addressing Structure:
IPv4 Address = 32 bit # written as dotted decimals
Always paired with a 32 bit mask
Computers evaluate &
E.G. 10101000 <- high-order that side, -> low order this side.
Network = group of hosts with identical network addresses.
Some portion of the low-order bits = host address.
From our 32 bits, the # of bits used in the host portion determines how many hosts we can have in our network.
E.G. if 200 hosts in our network. We need enough bits in the host portion to make 200+ numbers
2^7 = 128, 2^8 = 256, therefore 8 bits minimum are required to get 200+ hosts.
Tags: vlan, cisco, switch, ip, router, wan