How often does EIGRP send Hello messages on most networks?

EIGRP (Enhanced Interior Gateway Routing Protocol) is designed to support faster convergence and more efficient routing than its predecessor protocols. The frequency of Hello messages, which are crucial for maintaining neighbor relationships and topology awareness, is typically set to 5 seconds by default on most EIGRP-enabled interfaces.

These Hello messages allow routers to discover and monitor the status of neighboring routers. By sending these messages every 5 seconds, EIGRP can quickly detect if a neighbor has become unavailable, leading to a swifter reaction in changing routing paths compared to other protocols that might use longer intervals. This plays an essential role in ensuring network stability and the efficiency of routing decisions in a dynamic environment.

In specific scenarios, such as over slower or serial links, the interval can be adjusted. However, the standard and most common configuration across various network types is indeed 5 seconds, making this the correct answer.