# Frequently Asked Questions (FAQ)

See also

Glossary.

## How many hops are the circuits used to perform the measurements?

Two hops.

## How are relays selected to be measured?

The sbws scanner periodically refreshes its idea for what relays should be measured next. It prioritizese the measurement of relays that do not have recent results. In this way, relays that have just joined the network or have just come back online after a many-day period of being offline will be measured before relays that have been online constantly.

## How do sbws scanner results end up in the consensus?

The sbws scanner runs continuously to gather fresh data.

The sbws generate command takes the fresh data and generates a v3bw file.

The Tor directory authority parses the v3bw file and includes bandwidth information in its vote.

The authorities take the low-median of the bandwidths for each relay from all of the bandwidth authorities and use that in the consensus.

## Does sbws need any open ports?

No.

## How much bandwidth will the sbws scanner use?

Todo

answer this

## How much bandwidth will the webserver use?

Todo

answer this

## Should I run my own webserver? Use a CDN? Something else?

It’s up to you. Sbws is very flexible.

Todo

better answer.