Lec-42: Class B in IP addressing with Example | Classful Addressing in hindi with most easiest way

Summary

In this video, the host explains Class B IP addressing within the context of Classful Addressing. They walk through the structure of a 32-bit IP address, focusing on the fixed prefix of Class B and the range of its first octet, which spans from 128 to 191. The video explains the binary-to-decimal conversion for IP addresses, the number of networks and addresses possible in Class B, and how to calculate the network and host parts using bitwise operations. Finally, the video discusses the usable hosts in a Class B network, and how this addressing class is typically used in large networks like universities.

Takeaways

• 😀 Class B is part of Classful Addressing in IP addressing, alongside Class A, C, D, and E.
• 😀 Class B uses a 32-bit IPv4 address, divided into 4 octets (8 bits each), for a total of 32 bits.
• 😀 The first two bits of the first octet in Class B are fixed as '10', which helps identify the class of the IP address.
• 😀 The range for Class B IP addresses is from 128.0.0.0 to 191.255.255.255.
• 😀 To identify if an IP address belongs to Class B, check if the first octet is between 128 and 191.
• 😀 Class B IP addresses have 2 raised to the power of 30, or approximately 1 billion usable addresses.
• 😀 Class B supports **16,384 networks**, derived from 2 raised to the power of 14.
• 😀 Each Class B network can have **65,536 total IP addresses**, with **65,534 usable host addresses** after subtracting the network and broadcast addresses.
• 😀 In binary-to-decimal conversion, the binary digits are multiplied by increasing powers of 2, from right to left, to determine the decimal value.
• 😀 For each Class B network, the first two octets define the network, and the last two octets define the host addresses within that network.
• 😀 A simple example, such as the IP address **130.2.3.4**, shows how to calculate which Class the IP belongs to and how many hosts are possible in the network.

Q & A

What is the purpose of the prefix in Class B IP addresses?

The prefix helps identify the class of an IP address. In Class B, the first two bits of the first octet are fixed as '10', which helps in determining whether an IP address belongs to Class B or another class. These two fixed bits are used to identify Class B specifically, with the remaining 6 bits used to represent different values.

How can you determine if an IP address belongs to Class B?

To determine if an IP address belongs to Class B, examine the first octet. If the first two bits are '10', and the value of the first octet lies between 128 and 191 (inclusive), then the IP address belongs to Class B.

What is the range of IP addresses in Class B?

The range of Class B IP addresses spans from 128.0.0.0 to 191.255.255.255. This range is defined by the first octet, where values between 128 and 191 represent Class B.

How do you convert a binary number to decimal, and why is it important for IP addresses?

To convert a binary number to decimal, you multiply each bit by 2 raised to the power of its position, starting from the right (lowest bit). This conversion is essential for understanding IP addresses in both binary and decimal formats, as IP addresses are often represented in binary for network configurations but need to be understood in decimal for human comprehension.

How many IP addresses are available in Class B?

In Class B, there are 2^30 (approximately 1 billion) possible IP addresses. This is because Class B uses 30 bits for addressing, with 2 fixed bits for the prefix and the remaining bits for addressing hosts and networks.

What is the number of possible networks in Class B?

Class B allows for 2^14 (16,384) possible networks. This is calculated based on the first two octets, where 14 bits are available for network addressing, with the first 2 bits being reserved for the prefix.

How many hosts can be accommodated in each Class B network?

Each Class B network can accommodate 2^16 (65,536) hosts. However, two IP addresses in each network are reserved: the first for the network address and the last for the broadcast address, reducing the usable host addresses to 65,534.

Why do we subtract 2 from the total number of IP addresses in a Class B network?

We subtract 2 because the first IP address in the range is reserved for the network address and cannot be assigned to a host, and the last IP address is reserved for the broadcast address, which also cannot be assigned to a host.

What is the default subnet mask for a Class B network?

The default subnet mask for a Class B network is 255.255.0.0, which corresponds to a /16 prefix. This mask allows for 16 bits of the address to be used for network identification, leaving 16 bits for host addressing.

How is the network address calculated for an IP address like 130.2.3.4 in Class B?

To calculate the network address for an IP address like 130.2.3.4 in Class B, perform a bitwise AND operation between the IP address and the subnet mask (255.255.0.0). This operation isolates the network portion of the address, resulting in the network address 130.2.0.0.