Glossary
Review the definitions for terms used across Cloudflare’s BYOIP documentation.
| Term | Definition |
| address map | A data structure enabling customers with BYOIP prefixes or account-level static IPs to specify which IP addresses should be mapped to a zone’s DNS records when they are proxied through Cloudflare. |
| autonomous system numbers (ASNs) | A large network or group of networks that has a unified routing policy. Every computer or device that connects to the Internet is connected to an autonomous system. |
| Border Gateway Protocol (BGP) | The routing protocol for the Internet, which is responsible for picking the most efficient routes to deliver Internet traffic. |
| Internet Routing Registry (IRR) | A globally distributed database of routing information which contains announced routes and routing policies in a common format. Network operators use this information to configure backbone routers. |
| letter of agency | Sometimes referred to as a Letter of Authorization. A document that authorizes Cloudflare to advertise your prefixes. This is required so transit providers can accept the routes Cloudflare advertises on your behalf. |
| Resource Public Key Infrastructure (RPKI) | A cryptographic method of signing records that associate a route with an originating autonomous system number. |
| Unicast Reverse Path Forwarding (uRPF) | A security feature that can prevent spoofing attacks. |