$ sudo apt-get update
$ sudo apt-get install opendnssec-enforcer 

opendnssec-enforcer is installed in your system.

Make ensure the opendnssec-enforcer package were installed using the commands given below,

$ sudo dpkg-query -l | grep opendnssec-enforcer *

You will get with opendnssec-enforcer package name, version, architecture and description in a table

opendnssec-enforcer package basic information: