How to Monitor SSL Certificates and DNS Changes with Python
SSL expiry alerts are useful, but they only cover one part of a domain's operational state. A changed nameserver, a new mail provider, or an unexpected subdomain can be just as important.
I wanted one scheduled job that could watch all of those signals without maintaining separate WHOIS, DNS, TLS, and Certificate Transparency clients. The Domain Intelligence Suite returns the four data sets in one run, which makes the monitoring code mostly a matter of storing snapshots and comparing them.
What the monitor should detect
A useful domain monitor needs to report changes, not dump a fresh wall of JSON every morning. For each domain, we will track:
