Cisco Certified Network Associate (CCNA) 2026 – 400 Free Practice Questions to Pass the Exam

EIGRP, or Enhanced Interior Gateway Routing Protocol, utilizes the User Datagram Protocol (UDP) for the reliable transport of messages. Unlike TCP, which establishes a connection and ensures reliable delivery through acknowledgments and retransmissions, EIGRP implements a unique mechanism over UDP by utilizing a reliable transport layer for its routing updates.

While TCP is commonly associated with reliable transmission, EIGRP's design allows it to maintain efficiency in routing updates while still providing reliability without the overhead of maintaining a full connection like TCP. EIGRP messages, when sent, are handled using a specific UDP port (port 88), which provides an effective means for exchanging routing information among routers.

The other protocols mentioned, such as IP, are used for addressing and routing purposes but do not inherently include a method for guaranteeing message delivery, making UDP the correct choice for EIGRP's transport mechanism. Thus, utilizing UDP allows EIGRP to operate efficiently in a dynamic routing environment while ensuring that necessary routing updates are received reliably.