adns-tools software package provides Asynchronous-capable DNS client utilities, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install adns-tools
adns-tools is installed in your system.
Make ensure the adns-tools package were installed using the commands given below,
$ sudo dpkg-query -l | grep adns-tools *
You will get with adns-tools package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Network |
| Package | adns-tools |
| Version | 1.5.0~rc1-1+b1 [mips, mipsel], |
| Description | Asynchronous-capable DNS client utilities |
| Sub Section | Net |