Binary package “unbound” in ubuntu bionic

validating, recursive, caching DNS resolver

 Unbound is a recursive-only caching DNS server which can perform DNSSEC
 validation of results. It implements only a minimal amount of authoritative
 service to prevent leakage to the root nameservers: forward lookups for
 localhost, reverse for 127.0.0.1 and ::1, and NXDOMAIN for zones served by
 AS112. Stub and forward zones are supported.
 .
 This package contains the unbound daemon.