Routing protocols can be divided into 2 categories:

1. Interior Gateway Protocols (IGPs):
- IGPs are used within an autonomous system (AS), which is a network under a single administrative domain.
- These protocols are responsible for exchanging routing information between routers within the same AS.
- Examples of IGPs include Routing Information Protocol (RIP), Open Shortest Path First (OSPF), and Intermediate System to Intermediate System (IS-IS).

2. Exterior Gateway Protocols (EGPs):
- EGPs are used to exchange routing information between different autonomous systems.
- These protocols enable routers in different ASes to communicate and determine the best path for forwarding traffic between them.
- The most commonly used EGP is the Border Gateway Protocol (BGP), which is used in the global Internet.

Explanation:
Routing protocols are used by routers to exchange routing information and determine the best path for forwarding packets. They play a crucial role in ensuring efficient and reliable packet delivery in a network. These protocols can be categorized based on the scope of their operation.

Interior Gateway Protocols (IGPs) are used within a single autonomous system (AS). An AS is a network under a single administrative domain. IGPs are responsible for exchanging routing information between routers within the same AS. This allows routers to build and maintain a routing table that contains information about the network topology and the best path to reach different destinations within the AS. Examples of IGPs include RIP, OSPF, and IS-IS.

Exterior Gateway Protocols (EGPs), on the other hand, are used to exchange routing information between different autonomous systems. EGPs enable routers in different ASes to communicate and determine the best path for forwarding traffic between them. This is particularly important for interconnecting multiple ASes, such as in the case of the global Internet. The most commonly used EGP is BGP, which is responsible for exchanging routing information between ASes and determining the best path for traffic to traverse between them.

In summary, routing protocols can be divided into 2 categories: IGPs, which are used within a single AS, and EGPs, which are used to exchange routing information between different ASes.