When an EIGRP router starts, it sends a hello packet out of all interfaces.
Which type of packet do neighboring routers send in response?
When an EIGRP router starts, it sends hello packets out of each interface. Neighboring routers respond with update packets. These update packets are sent reliably, and must be acknowledged with an ACK packet from the EIGRP router.
EIGRP makes neighbor relationships simple. If a router hears a hello from a new neighbor, it sends that neighbor updates for all routes that it knows. This is different from Open Shortest Path First (OSPF), which has a complex series of rules governing how neighbor relationships are formed and how databases are synchronized. When changes to the network occur in OSPF, updates packets route reliable change information only to the affected routes.
Queries and replies in EIGRP only occur when a router loses a route to a network and is actively seeking a replacement route.
Layer 3 Technologies
Describe EIGRP packet types