What is the size of a RIP message that advertises only one network?

A RIP (Routing Information Protocol) message that advertises only one network consists of the RIP header and a single route entry. The RIP header is 4 bytes, and each route entry is typically 20 bytes. Therefore, the total size of a RIP message advertising one network is 4 bytes (header) + 20 bytes (route entry) = 24 bytes.