What is Network ID?
A network ID also known as NetID is a fixed bit in the IP address that represents the entire network of any host It is connected to the network. i.e., it tells the network of the host by which the host is connected.
The total size of the IP address is 32 bits and the IP address is divided into four octets each of size is 8 bits. And further, divide into NID and HID. Let’s discuss each class in detail.
Class A: The first octet represents NID so there are 8 bits for NID and 24 bits for HID. And the first bit of the first octet is always 0.
Class B: The first two octets represent NID so there are 16 bits for NID and 16 bits for HID. And the first two bits of the first octet are fixed i.e., 10.
Class C: The first three octets represent NID so there are 24 bits for NID and 8 bits for HID. The first three bits of the first octet are fixed i.e., 110.
Class D: All bits are fixed for NID.
Class E: All bits are fixed for NID.
What is “network ID” and “host ID” in IP Addresses?
Initially in 1980 IP address was divided into two fixed parts NID=8 bit and HID=24 bit. NID (Network ID) represents the entire network for a specified host. HID (Host ID) represents a specified user IP address within the network. So there are only 28 i.e., 256 networks are available and there are 224 i.e., 16M hosts per network. If even a small organization wants to purchase a network then it should buy one network in which there are 16M hosts that can be connected this is the drawback of this fixed representation of IP address.
IP addresses are divided into 5 classes:
- Class A is used for big networks such as ISP networks.
- Class B is used by big organizations.
- Class C is used by small organizations.
- Class D no NID and HID all 28 bits are used to define the multicast address.
- Class E is reserved for research and future purchases.