From MozillaZine Knowledge Base
When a site is classified as safe or unsafe, a partial hash is generated of a fragment of the URL. This can be compared against the remote database to return a complete hash and extra metadata. When the hash is sent, a number of random hashes are sent along with it to obscure the “real” URL. This preference determines how many random entries are sent.
Possible values and their effects
A non-negative integer indicating the number of random entries to send with the actual hash when comparing a URL against the remote database. Default value is 4.
First checked in
Has an effect in