Unbound is a validating, recursive, and caching DNS resolver.
The C implementation of Unbound is developed and maintained by 
NLnet Labs. It is based on ideas and algorithms taken from a java 
prototype developed by Verisign labs, Nominet, Kirei and ep.net.

Unbound is designed as a set of modular components, so that also DNSSEC 
(secure DNS) validation and stub-resolvers (that do not run as a server,
but are linked into an application) are easily possible.

A user and group are recommended to run Unbound. The following should
not conflict with anything else on SlackBuilds:

  groupadd -g 304 unbound
  useradd -r -u 304 -g unbound -d /etc/unbound/ -s /sbin/nologin -c \
  'Unbound DNS resolver' unbound

Optional DNSCrypt support is provided. To enable:

  DNSCRYPT=yes ./unbound.SlackBuild

This will require libsodium which is available at SlackBuilds