named-checkconf: Validate that A records contain valid IP address (e.g. not a CNAME)
Description
Recently ran into an issue with named failing to start on a deployment which appears to be due to the following type of entry:
example IN A example.com (no trailing period either)
We discussed adding some validation which led us to the named-checkconf tool, as referenced in https://www.cyberciti.biz/tips/howto-linux-unix-check-dns-file-errors.html. The tool doesn't appear to check for valid IPs and I think it could be a good place to put this logic. I tested locally and it doesn't appear to catch an invalid IP for an A record.
Request
Can we consider adding validation support for valid IP addresses for A records in named-checkconf?