Meaning – The term hello message, refers to the message sent periodically to establish and test reachability between routers or between routers and hosts.

In reply to the client hello message, the server sends a message containing the server’s SSL certificate, the server’s chosen cipher suite, and the “server random,” another random string of bytes that’s generated by the server.

The term hello message also refers to the message defined by the Hello protocol as an Interior Gateway Protocol (IGP).

The HELLO protocol uses a distance-vector algorithm, like the Routing Information Protocol and the Gateway-to-Gateway protocol. What’s interesting about it, however, is that, unlike RIP and GGP, HELLO does not use hop count as a metric.

Example of usage“The name “HELLO” is capitalized, but is not an acronym; it simply refers to the word hello, since the protocol uses messages that are sort of analogous to the routers talking to each other.”