The Internet Routing Registry: History and Purpose
The IRR was established in 1995. Its purpose is to ensure stability and consistency of the Internet-wide routing by sharing information between network operators. The IRR consists of several databases in which network operators can publish their routing policies and their routing announcements such that other network operators can make use of the data. In addition to making Internet topology visible, the IRR is used by network operators to look up peering agreements, determine optimal policies, and more recently, to configure their routers.
Each Regional Internet Registry has its own network information database, part of which is used for routing information. RADB and RIPE are both public databases (registries) where any ISP can publish their policies.
Most of these databases also mirror each other. This means registering is only necessary in one database. To retrieve info from all the mirrored databases, you can query RIPE Database using the "-a" flag.
The benefits of the IRR are only realised when registered routing policies are kept up to date, and reflect routing announcements in the 'real world'.