Lec-44: Class D & Class E in IP addressing with Example | Classful Addressing | Network Layer

Summary

In this video, the topic of Class D and Class E IP addressing is explored within the context of Classful Addressing. Class D (224-239) is dedicated to multicast addresses, while Class E (240-255) is reserved for experimental or military use. Both classes have fixed first octet values, with no host or network allocation, leading to a significant waste of IP addresses. This inefficiency contributed to the shift towards Classless Addressing after 1993. The video explains how to identify these classes based on their first octet and highlights their reserved nature and lack of usage for general networking purposes.

Takeaways

• 😀 Class D and Class E are part of Classful IP Addressing, with specific uses and reserved IP ranges.
• 😀 Class D IP addresses range from 224.0.0.0 to 239.255.255.255, reserved for multicasting and group communication.
• 😀 Class E IP addresses range from 240.0.0.0 to 255.255.255.255, reserved for military purposes and not for general use.
• 😀 In both Class D and Class E, the first 4 bits of the IP address are fixed ('1110' for Class D, '1111' for Class E).
• 😀 Class D allows for `2^28` unique IP addresses, roughly 250 million, but does not have hosts or networks.
• 😀 Class E also has `2^28` unique IP addresses, about 250 million, but is reserved for military applications with no network or host use.
• 😀 Both Class D and Class E are characterized by the lack of network and host functionality, meaning they are not used for regular IP assignments.
• 😀 Despite the large number of IP addresses in Class D and Class E, these addresses are not fully utilized, leading to wasted IP space.
• 😀 Class D IP addresses are used for special purposes like group broadcasting, while Class E is reserved exclusively for military uses.
• 😀 The Classful Addressing system, which includes Class D and E, was eventually replaced by Classless Addressing to accommodate the growing demand for IP addresses.

Q & A

What is the primary focus of the video script?

The primary focus of the video script is to explain Class D and Class E IP addressing in the context of Classful Addressing, including their ranges, uses, and characteristics.

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

You can determine if an IP address belongs to Class D by examining its first octet. If the first four bits are `1110`, the IP address belongs to Class D. In decimal terms, this corresponds to addresses in the range 224 to 239.

What is the range of IP addresses for Class D?

The range of IP addresses for Class D is from `224.0.0.0` to `239.255.255.255`.

How many possible IP addresses are there in Class D?

Class D contains 2^28 possible IP addresses, which is approximately 250 million IP addresses.

What is the purpose of IP addresses in Class D?

IP addresses in Class D are reserved for **multicasting**, **group broadcasting**, and **group emailing**. These addresses are used by groups of users, such as in research or online group communications.

What is a major disadvantage of Class D IP addresses?

A major disadvantage of Class D IP addresses is that a large portion of them remains unused because there are only a limited number of groups using these addresses, despite the vast number of available addresses (approximately 250 million).

What are Class E IP addresses reserved for?

Class E IP addresses are reserved for **military purposes** and are not available for general use.

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

To determine if an IP address belongs to Class E, check the first octet. If the first four bits are `1111`, the IP address belongs to Class E. In decimal terms, this corresponds to addresses in the range 240 to 255.

What is the range of IP addresses for Class E?

The range of IP addresses for Class E is from `240.0.0.0` to `255.255.255.255`.

What is the total number of IP addresses in Class E, and why are they considered inefficient?

Class E also contains 2^28 IP addresses, about 250 million. These addresses are inefficient because they are reserved for military use, resulting in unused IP addresses despite the increasing demand for IP addresses from general users.