IP addressing and Subnetting | CIDR | Subnet | TechTerms

Summary

This script explains the concept of IP addresses and subnetting, focusing on how hosts and routers interact with the internet. It defines the boundary between a host and its communication link as an interface, emphasizing that IP addresses are linked to interfaces, not devices. The script covers the format of IPv4 addresses, including the 32-bit structure and dotted-decimal notation. It discusses subnetting, with examples of network addresses and the use of CIDR for address assignment. Finally, it highlights how organizations can create multiple subnets within their allocated IP address space.

Takeaways

• 😀 A host is connected to the Internet via a communication link, and the boundary between the link and the host is called an interface.
• 😀 Typically, a host has only one interface, while a router has multiple interfaces, each connected to a different link.
• 😀 Hosts and routers send and receive IP datagrams through their interfaces, which must each have an IP address.
• 😀 An IP address is associated with an interface, not the host or router itself.
• 😀 The binary number system uses two symbols – 0 and 1 – and sequences of 0s and 1s represent data such as IP addresses.
• 😀 An IPv4 address is 32 bits (4 bytes) long, typically expressed in dotted-decimal notation (e.g., 192.168.1.1).
• 😀 Each IP address is divided into parts by the subnet, which defines the range of addresses within the network.
• 😀 Subnets have addresses such as 223.1.1.0/24, where '/24' is the subnet mask indicating that the first 24 bits are shared among all addresses in the subnet.
• 😀 CIDR (Classless Interdomain Routing) uses a generalised IP address format a.b.c.d/x, where 'x' indicates the number of bits that define the network prefix.
• 😀 CIDR allows for flexible and efficient IP address management by enabling subnetting within an organisation’s allocated IP space, where the leftmost 'x' bits define the network prefix.

Q & A

What is the difference between a host and a router in terms of interfaces?

A host typically has only one interface, while a router has two or more interfaces, as it connects to multiple networks.

How are IP addresses linked to devices?

IP addresses are linked to the interfaces of devices (hosts or routers), not directly to the device itself. Each interface on a device can have a unique IP address.

What is the significance of the binary number system in IPv4 addresses?

The binary number system is used to represent IPv4 addresses, which are 32-bit long. Each IPv4 address is divided into 4 bytes (32 bits), with each byte being represented by 8 binary digits.

What is the meaning of 'dotted-decimal notation' in IPv4 addresses?

Dotted-decimal notation is the format used to represent IPv4 addresses, where the 32-bit address is divided into four 8-bit sections (bytes) and each section is expressed as a decimal number, separated by dots.

What is a subnet, and how does it relate to IP addresses?

A subnet is a network that consists of devices (hosts and routers) with IP addresses sharing a common network portion. Each subnet has a unique address, and the subnet mask determines the division of IP addresses into network and host portions.

What does '/24' represent in the subnet address '223.1.1.0/24'?

'/24' indicates that the first 24 bits of the IP address are used for the network portion of the address. This means that all devices in this subnet share the same leftmost 24 bits of their IP addresses.

How are CIDR and subnet masks related?

CIDR (Classless Interdomain Routing) uses a flexible subnetting approach where the subnet mask is represented as '/x'. This 'x' defines the number of bits allocated for the network portion of the IP address, allowing for more efficient address allocation than traditional class-based addressing.

What is the function of the network prefix in a CIDR address?

The network prefix in a CIDR address, denoted as 'a.b.c.d/x', specifies the number of bits that represent the network portion of the address. The remaining bits can be used for host addresses within that network.

How does CIDR help organizations manage IP address allocation?

CIDR allows organizations to be assigned a range of IP addresses with a common network prefix, and it provides flexibility for further subnetting within the allocated address space. This allows efficient use of IP address resources.

What is the importance of subnetting within an organization's network?

Subnetting allows an organization to divide its network into smaller, more manageable subnets. This helps optimize network performance, improve security, and make better use of the allocated IP address space.