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What is an IP address?
An IP address is A unique identifier assigned to each device connected to a computer network
The most common analogy for an IP address is the postal service. For the postal service to work, every house needs to have its own, unique address. If you need to send a letter, you'll need to write the destination address on the envelope. That way, when you send your letter, the postman knows exactly where to deliver it.
Computers work in the same way. Each computer in a network needs to have a unique address, called an IP address.
and when sending data to a computer, just like letters, we need to add the destination address. We also need to include a return address, so they know where to reply.
An IPv4 address is 32-bits in length. It contains 4 sections, which are called octets. These octets are separated by periods. Each octet can, in theory, contain any number between 0 - 255
The IP address is separated into two parts. The first part represents the network and the second part represents the host. To know which part of an IP address represents the network, we use something called a subnet mask. In its simplest form, wherever you see 255. this is the network part of the address and wherever you see a zero, this is the host part of the address,
IP Address Classes
It was decided to split all of the available addresses into groups called classes. The idea was to make address allocation scalable.
We have class A, class B, and class C. Class D and E are reserved.
Class A addresses are between 1.0.0.0 to 126.255.255.255
0.0.0.0 and 127.0.0.0 are class A addresses but are reserved
With a subnet mask of 255.0.0.0
Max Hosts: 16,777,214
Class B addresses are between 128.0.0.0 to 191.255.255.255
With a subnet mask of 255.255.0.0
Max Hosts: 65,534
and class C addresses are between 192.0.0.0 - 223.255.255.255
With a subnet mask of 255.255.255.0
Max Hosts:254
Private IP Addresses
But there’s a problem. The problem is that no one could have predicted the massive explosion of computers and the internet. In fact, there are no more unallocated Ipv4 addresses left. That is why the new Ipv6 has been designed to give us more than enough IP addresses for everyone.
To help prolong the life of IPv4, we have carved out a small section from all three classes and called them, private IP addresses.
Private class A addresses are between 10.0.0.0 - 10.255.255.255
Private class B addresses are between 172.16.0.0 - 172.32.255.255
Private class C addresses are between 192.168.0.0 - 192.168.255.255
#ccna #cisco #networking