In computer networking, hop count refers to the number of routers through which data must pass between source and destination. Each router along the data path constitutes a hop

Hop (networking)

Data packets often have to go through routers , if not several, before they reach their final destination. Each time packets are passed to the next router a hop occurs. .- Hop Count :The distance between two hosts...

, as the data is moved from one Layer 3 network to another. Hop count is therefore a basic measurement of distance in an network.
By itself, hop count is not a useful metric for determining the optimum network path, as it does not take into consideration the speed

Bandwidth (computing)

In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...

, load, reliability, or latency of any particular hop, but merely the total count. Nevertheless, some routing protocols

Routing protocol

A routing protocol is a protocol that specifies how routers communicate with each other, disseminating information that enables them to select routes between any two nodes on a computer network, the choice of the route being done by routing algorithms. Each router has a priori knowledge only of...

 such as RIP

Routing Information Protocol

The Routing Information Protocol is a distance-vector routing protocol, which employs the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from the source to a destination. The maximum number of hops allowed for RIP is 15....

 use hop count as their sole metric.

Hop counts are often useful to find faults in a network, or to discover if routing is indeed correct. Utilities such as ping

Ping

Ping is a computer network administration utility used to test the reachability of a host on an Internet Protocol network and to measure the round-trip time for messages sent from the originating host to a destination computer...

 and traceroute

Traceroute

traceroute is a computer network diagnostic tool for displaying the route and measuring transit delays of packets across an Internet Protocol network. Traceroute is available on most operating systems....

are used in this capacity—by calculating the hop count to a given destination, as well as enumerating each hop along the way.