What is a Network Address? – GeeksforGeeks

A computer network is a group of some interconnected computers that are sharing a common or different resources provided on or by network nodes. These sharing or communication between the machines is governed by some set of rules or network protocols. These computers or machines are identified by network addresses, and may have hostnames.

A Network Address is a logical or physical address that uniquely identifies a host or a machine in a telecommunication network. A network may also not be unique and can contain some structural and hierarchical information of the node in the network. Internet protocol (IP) address, media access control (MAC) address and telephone numbers are some basic examples of network addresses. It can be of numeric type or symbolic or both in some cases.

Network Addressing :

It is the prime responsibility of the network layer to assign unique addresses to different nodes in a network. As mentioned earlier they can be physical or logical but primarily they are logical addresses i.e. software-based addresses.  The most widely used network address is an IP address. It uniquely identifies a node in an IP network. An IP address is a 32-bit long numeric address represented in a form of dot-decimal notation where each byte is written in a decimal form separated by a period. For example 196.32.216.9 is an IP address where 196 represents first 8 bits, 32 next 8 bits and so on. The first three bytes of an IP address represents the network and the last byte specifies the host in the network. An IP address is further divided into sub classes :

• Class A : An IP address is assigned to those networks that include large number of hosts.
• Class B : An IP address is assigned to networks range from small sized to large sized.
• Class C : An IP address is assigned to networks that are small sized.
• Class D : IP address are reserved for multicast address and does not possess subnetting.
• Class E :  An IP address is used for the future use and for the research and development purposes and does not possess any subnetting.

An IP address is divided into two parts:

1. Network ID :  represents the number of networks.
2. Host ID : represents the number of hosts.

Norms to assign Network ID :

1. For the hosts located in the same network, share the same network ID.
2. It cannot start with 127 as 127 is used exclusively by Class A.
3. If all the bits of the network ID are set to 0, it could not be assigned as it specifies a particular host on the local network.
4. If all the bits of the network ID are set to 1, it could not be assigned as it is reserved for multicast address.

Norms to assign Host ID :

1. It must be unique within any network.
2. If all the bits of the host ID are set to 0, it could not be assigned as it is used to represent the network ID of the IP address.
3. The Host ID with all the bits set to 1 are reserved for multicast address.

Classful Network Addressing :

ClassLeading BitsNET ID BitsHOST ID BitsNumber of NetworksAddresses per NetworkRangeA0824272240.0.0.0 to 127.255.255.255B101616214216128.0.0.0 to 191.255.255.255C11024822128192.0.0.0 to 223.255.255.255D1110Not definedNot defined Not definedNot defined224.0.0.0 to 239.255.255.255E1111Not definedNot defined Not definedNot defined240.0.0.0 to 255.255.255.255

For more on network addressing and architecture refer to this article. 

My Personal Notes

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