IP addresses

 IP addresses

An IP address (Internet Protocol address) is a unique numerical label assigned to devices connected to a network that uses the Internet Protocol for communication. It acts like an online address,  identifying a specific device on the internet or a local network.

Here's a breakdown of key concepts related to IP addresses:

Types of IP Addresses:

IPv4 (Internet Protocol Version 4): The most widely used version for a long time, but the available addresses are nearing depletion. It consists of four numbers separated by periods, each number ranging from 0 to 255. (e.g., 192.168.1.1)

IPv6 (Internet Protocol Version 6): The next generation of IP addresses designed to address the limitations of IPv4. It has a more extensive address space and a different format with eight groups of hexadecimal digits separated by colons. (e.g., 2001:db8:0:1234:0:567:8:1)

Public vs. Private IP Addresses:

Public IP Addresses: Uniquely identify a device on the internet and are assigned by internet service providers (ISPs). They are routable, meaning they can be accessed from anywhere on the internet.

Private IP Addresses: Used for devices on a local network and are not routable on the public internet. Common private IP address ranges include 10.0.0.0 to 10.255.255.255, 192.168.0.0 to 192.168.255.255, and 172.16.0.0 to 172.31.255.255.

Subnet Mask:  A binary mask that helps differentiate between the network part and the host part of an IP address. It  determines the size of the network and the number of devices that can be connected on that network.

IP Address Assignment:  Public IP addresses are typically assigned dynamically by ISPs using DHCP (Dynamic Host Configuration Protocol). Private IP addresses can be assigned statically (manually configured) or dynamically using DHCP on a local network.

Functions of IP Addresses:

Identification: Uniquely identifies devices on a network.

Location: While not an exact physical location, IP addresses can be used to determine the general geographic location of a device.

Routing: Enables data packets to be directed to the correct device on a network.

Network and host addresses

An IP address, as you learned earlier, acts like an address for a device on a network. It's like a unique identification code that allows other devices to find and communicate with it. But an IP address itself is made up of two parts: the network address and the host address.

Network Address:

Identifies the specific network a device belongs to.  Think of it like a neighborhood name within a city.  All devices on the same network share the same network address.

It's derived by applying a subnet mask to the IP address. A subnet mask is a series of ones and zeros that separates the network part from the host part of the IP address.

Example: Let's say a device has an IP address of 192.168.1.100 and the subnet mask is 255.255.255.0 (common for home networks). Here, the first three octets (192.168.1) represent the network address, identifying the specific network that device belongs to.

Host Address:

Identifies a specific device within a network.  Imagine it like a house number within a neighborhood.  Each device on the same network has a unique host address within that network.

It's obtained by performing a bitwise AND operation between the IP address and the subnet mask. This operation takes the corresponding bits from the IP address and subnet mask and returns a 1 only if both bits are 1.

Continuing the example: The host address in this case would be 100 (decimal representation of the last octet 00000011 in binary). This identifies the specific device with IP 192.168.1.100 on the network 192.168.1.

Why separate Network and Host Addresses?

Network Efficiency:  By dividing the IP address into network and host parts,  networks can be efficiently managed. Routers can use the network address to determine where to send data packets, reducing unnecessary traffic within a network.

Scalability:  The network address allows for a larger number of devices to be connected to a network. With more bits allocated to the host address,  a larger pool of unique addresses is available within each network.

Analogy:

Imagine a large apartment building. The building address (like 123 Main Street) is the network address, identifying the building itself.  Each apartment within the building has a unique number (like apartment 5B) which is the host address,  identifying a specific residence within the building.

How many classes of Ip address we have

There are traditionally five classes of IP addresses defined in IPv4 (Internet Protocol version 4), the most widely used version for a long time:

Class A: Designed for very large networks with a vast number of potential hosts.  Class A addresses use the first octet (out of four) for the network address and the remaining three octets for the host address.  This allows for a maximum of 128 (2^7) Class A networks but limits the number of hosts per network.  Due to depletion of IPv4 addresses, Class A is rarely used anymore.

Class B: Suitable for medium-sized networks with a moderate number of hosts.  Class B addresses use the first two octets for the network address and the remaining two octets for the host address.  This allows for more Class B networks (16,384 or 2^14) compared to Class A, with a good balance between network and host capacity.

Class C:  The most common class used for smaller networks like home networks or small businesses.  Class C addresses uses it first three octets for the network address and the last octet for the host address.  This provides a significant number of Class C networks (over two million or 2^21) but limits the number of hosts per network (254 or 2^8).

Class D:  Reserved for multicast addressing, which allows data to be sent to a group of devices simultaneously. Class D addresses use the first four bits as 1101, followed by a variable-length network address portion.

Class E:  Reserved for future use or experimental purposes. Class E addresses use the first four bits as 1110, followed by the remaining bits for the network or host address depending on specific use.

Understanding IP addresses is essential for anyone who uses the internet or works with computer networks. They play a fundamental role in how devices communicate and access information online.