Networking, Addressing, and Communication Lesson 003: Classful vs. Classless Addressing

What two predefined classes is IP address structure devided into?

Classful addressing and classless addressing.

What is the purpose of having predefined classes for IP address structure?

It made allocation and management easier during the early days of the Internet with smaller, localized networks.

Classful Addressing

Divides IPv4 addresses into five groups.

What are the 5 classes of classful addressing?

Class A, Class B, Class C, Class D, and Class E.

How are different IPv4 address classes defined?

By the value of the first octet or first set of numbers in the dotted-decimal notation.

what does each IPv4 class have?

A default subnet mask dictating the division of network and host portions of the IP address.

What is the value range in the first octet in the Class A IPv4 category?

1-127.

What is the default subnet mask of a Class A network?

255.0.0.0.

How many possible hosts can be supported by a Class A network?

16,777,216.

What are class A networks usually used for?

For very large companies or government/government agencies.

What is the value range in the first octet in the Class B IPv4 category?

128-191.

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

255.255.0.0.

How many possible hosts can be supported by a Class B network?

65,536.

What are Class B networks usually used for?

Medium or large businesses or large offices.

What is the value range in the first octet in the Class C IPv4 category?

192-223.

What is the default subnet mask of a Class C network?

255.255.255.0.

What are Class C networks usually used for?

Home or small office use.

Why can 2 IP addresses in every network not be used by actual users?

Because one needs to be set aside to identify the network itself, and one needs to be used as a broadcast IP.

What is the value range in the first octet in the Class D IPv4 category?

224-239.

What are Class D networks used for?

Multicasting.

Multicasting

The method of sending data from one endpoint, to multiple other endpoints.

What are some examples of multicasting?

Video streaming, financial tickers, software updates, and network protocol updates.

What is the value range in the first octet in the Class E IPv4 category?

240-255.

How many possible hosts can be supported by the Class E IPv4 category?

268 million.

What is special about the Class E IPv4 category?

This range of IPv4 addresses is used for experimental purposes and are not used for regular Internet traffic.

Why is classful addressing considered wasteful?

Because addresses can only be allocated in chunks and any unused IP addresses cannot be reused.

Classless Inter-Domain Routing

Replaced the fixed class system with a more flexible approach to subnetting and address allocation.

When was classless addressing introduced?

In the 1990s.

What does CIDR stand for?

Classless Inter-Domain Routing

What does CIDR notation specify?

The subnet mask with a slash ("/") and the number of network bits.

What does the number in CIDR notation represent?

The number of network bits that represents the network portion of the address.

What is a proper example of proper CIDR notation?

192.168.1.0 with a subnet mask of 255.255.255.0 would have a CIDR notation of 192.168.1.0/24.

What capability does CIDR notation provide?

Enables subnetting to create a subnet from a large network.

How is subnetting larger networks accomplished in CIDR notation?

By borrowing bits from the host portion of the address and reallocating them to the network portion of the address.

What is the performative benefit of using subnets?

Subnets, especially smaller subnets reduce network congestion and isolate communication.

What benefit does subnetting provide concerning security?

Allows for the separation of sensitive areas of a network, like server farms or employee workstations, like setting up a guest network in Wi-Fi configurations.

Supernets

The combining of multiple networks to create larger address blocks.

How is a supernet created?

By decreasing network bits to merge smaller subnets into a larger network.

What is the benefit of supernetting?

Simplifies routing by consolidating routing tables.

Who would most likely use supernetting and why?

ISPs to manage larger address blocks.

What are the overall benefits due to the implementation of CIDR?

Extended the usability, scalability, and address demands of IPv4, and paved the way for innovations like VPNs and cloud computing, which both need efficient IP address management.