# Service location broker - slobrok

[](/en/operations/self-managed/slobrok.html.md "View as Markdown") 

Slobrok is an acronym for _Service Location Broker_, and it is a name service used in Vespa. The service listens on a specific port - use [vespa-model-inspect](../../reference/operations/self-managed/tools.html#vespa-model-inspect) to find the `Slobrok` service's port number.

Slobrok is running by default on the administration node as well as one or two other random nodes for redundancy. Best practise for a multi-node, high-availability application is found in the [multinode-HA](https://github.com/vespa-engine/sample-apps/tree/master/examples/operations/multinode-HA) sample application. In this application, slobrok instances are hosted on nodes running [config servers](configuration-server.html). The motivation is, like the config servers, Vespa requires slobrok to be up for services to function. Operating slobrok is the same as config servers, too - three is enough for most applications. As slobrok requires minimal system resources, it does not impact other services running on the same node -\> using config server nodes is ideal.

Clients, like the [Document API](/en/reference/api/api.html), will do lookups on any of the service location broker nodes. Slobrok is not used in the query pipeline. The [cluster-controller](../../content/content-nodes.html#cluster-controller) uses slobrok to evaluate service availability.

The Slobrok process looks like:

```
```
$ ps ax | grep vespa-slobrok
93906 ?? SJ 2:31.52 $VESPA_HOME/sbin/vespa-slobrok -p 19100 -c slobrok.0
```
```

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