Before we dive into the specifics, let’s take a moment to revisit what RFCs are. Standing for “Request for Comments,” RFCs are documents that establish and discuss many protocols and considerations that underlie the internet as we know it. They are the blueprints of the internet, laying the groundwork for its many mechanisms and procedures.
Now, let’s talk about RFC 5735, also known as “Special Use IPv4 Addresses.” Similar to its sibling standard, RFC 6761, RFC 5735 deals with special use cases. However, while RFC 6761 addresses special-use domain names, RFC 5735 concerns special-use Internet Protocol (IP) addresses.
An IP address is a unique string of numbers separated by periods that identifies each computer using the Internet Protocol to communicate over a network. Just as postal addresses allow letters to be delivered to the right locations, IP addresses guide the internet traffic to its correct destination.
RFC 5735 outlines a series of IPv4 address blocks reserved for special purposes. Let’s go through a few examples to understand its practical implications:
1. Private Networks (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16): These IP ranges are reserved for use within private networks, such as your home or office network. They are not routable on the public internet, which means you can’t reach a device over the internet using these addresses alone.
2. Loopback (127.0.0.0/8): This range is reserved for loopback addresses. The most commonly used IP from this block is 127.0.0.1, which your computer uses to refer to itself.
3. Link-Local (169.254.0.0/16): These addresses are used when a device needs to communicate with other devices on the same network, but a DHCP server cannot assign it an IP.
4. Test-Net (192.0.2.0/24, 198.51.100.0/24, and 203.0.113.0/24): These are reserved for documentation and network testing. They’re the IP equivalent of “.test” and “.example” domain names.
RFC 5735 is vital in maintaining an orderly and efficient network structure. Clearly outlining which addresses serve which functions ensures that IP addresses can be used effectively and prevents confusion or miscommunication within the network.