{"id":684,"date":"2025-06-02T06:41:50","date_gmt":"2025-06-02T06:41:50","guid":{"rendered":"https:\/\/datadandies.nl\/?p=684"},"modified":"2025-06-05T06:29:16","modified_gmt":"2025-06-05T06:29:16","slug":"classless-inter-domain-routing-cidr-to-allocate-ip-addresses-in-a-network-like-aws-vpc-and-structure-of-an-ip-address","status":"publish","type":"post","link":"https:\/\/datadandies.nl\/index.php\/2025\/06\/02\/classless-inter-domain-routing-cidr-to-allocate-ip-addresses-in-a-network-like-aws-vpc-and-structure-of-an-ip-address\/","title":{"rendered":"Classless Inter-Domain Routing (CIDR) to allocate IP addresses in a network like AWS VPC and structure of an IP address"},"content":{"rendered":"\n

Classless Inter-Domain Routing is a way to allocate IP addresses within a network. Every machine that is connected to the internet has a unique number, called an IP address.<\/p>\n\n\n\n

With CIDR you can create a range of private IP addresses for a VPC. These IP addresses are allocated to resources that you deploy within your VPC.<\/p>\n\n\n\n

The IP addresses are private, unless you explicitly set up internet gateways or something similar in your VPC.<\/p>\n\n\n\n

Are you deploying an EC2 instance within a subnet within your VPC? Then an IP address will be allocated to it.<\/p>\n\n\n\n

Imagine you deployed a VPC with a CIDR block containing a range 10.0.0.0\/29. The 29 tells you how many bits are reserved for the network part of the IP address (29 bits of 32). This means that you have 32-29 = 3 \u2192 2^3 = 8 IP addresses available for the subnet. Edit: after having this post fact-checked by AI it got smart with me and told me only 6 IP addresses were usable because 1 is reserved for the network address and 1 for the broadcast address<\/p>\n\n\n\n

It can be useful to limit the number of hosts for a subnet in order to keep more IP addresses available. Some resources that live in your VPC like a load balancer, only need a few IP addresses after all.<\/p>\n\n\n\n

By the way, a load balancer is a tool that directs traffic to resources like servers within your VPC in order to prevent overloading a resource; it \u201cspreads\u201d the load, so to speak.<\/p>\n\n\n\n

Now, if you want to get even more \u201czero and one-sy\u201d, take a look at the image below. It shows how an IP address is structured. An IP address can contain a maximum of 32 bits divided into 4 binary octets of 8 bits. Again, the image below should help clarify the structure.<\/p>\n\n\n\n

\"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

Classless Inter-Domain Routing is a way to allocate IP addresses within a network. Every machine that is connected to the internet has a unique number, called an IP address. With CIDR you can create a range of private IP addresses for a VPC. These IP addresses are allocated to resources that you deploy within your…<\/p>\n

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