I was playing around with testssl.sh and got this error.

Fatal error: Neither "dig", "host", "drill" or "nslookup" is present

Fatal error: No IPv4/IPv6 address(es) for "geekflare.com" available

It was on CentOS 7 and if you are having the same issue then here is how you can fix it.

This happens when a program can’t find any utility to resolve the IP or domain. You can install the bind-utils to fix the error.

yum install bind-utils -y

Run the program again and it should be ok.