Cisco ICND1 Flashcard: Classes of IP Addresses, Public Routable and Private

This is a quick reference study guide for IP v4 Addressing.

The number in the first octet
Class A 0-126 network.host.host.host
Class B 128-191 network.network.host.host
Class C 192-223 network.network.network.host
Class D 224-239 Multicast addressing
Class E 240-255 Research and Development

Private IP Address Ranges
Class A 10.0.0.0 - 10.255.255.255
Class B 172.16.0.0 - 172.31.255.255
Class C 192.168.0.0 - 192.168.255.255

Hints on addressing
Class A - first binary bin in the first octet is 0 always (so it cannot be 128 which is the next class)
Class B - first two bits of binary in the first octet is 10 (so it is 128 and up)
Class C - first three bits of binarary in the first octet is 110 (so its 192 and up)

Maximum number of hosts
Class A 2^24 -2 = 16,777,214
Class B 2^16 -2 = 65,534
*Class C 2^8 -2 = 254

Class C addressing is most commonly used for small networks
Using 6 subnet bits, how many usable subnet bits are created?
62 = 2^6 - 2
What is the maximum number of bits to borrow to create a subnet for Class C network?
6
Reserved IP addresses
Network address 172.16.0.0
Directed broadcast 172.16.255.255
Local broadcast 255.255.255.255
*Local loopback 127.0.0.0 to 127.255.255.255
Auto-configuration 169.254.0.0/16 to 169.254.255.255

Use the local loopback address to test the NIC card, sending a ping to your own network interface.