Which routing protocol primarily uses updates in the form of complete routing tables?

RIP, or Routing Information Protocol, primarily utilizes full routing table updates. This means that when RIP sends its routing updates, it transmits the entire routing table to all neighbors at regular intervals, rather than just the changes or differences, which is known as Dijkstra's algorithm or incremental updates. This can be beneficial in smaller networks where complete routing tables are manageable because it simplifies the routing process.

RIP's approach to updates makes it easier for all routers on the network to be synchronized with the current routing information, but it can also lead to inefficiencies in larger networks due to its bandwidth consumption and slower convergence times compared to distance vector protocols or link-state protocols like OSPF and EIGRP, which use more efficient methods such as sending only changes in routing information or a combination of both. IS-IS, another routing protocol, also uses link-state mechanisms rather than sending complete routing tables. Hence, RIP stands out for its use in transmitting full routing tables periodically.