Monitoring hosting

Common checks:

SSL server score plus many details: https://ssllabs.com
State-of-the-art (Dutch indication): https://nl.internet.nl   /  https://en.internet.nl
Functioning of a DNS (informative): https://dnsspy.io
Broken links, performance, etcetera: https://ohdear.app/
DNS report: https://mxtoolbox.com/SuperTool.aspx?action=dns
Server / site score (plus list subdomains): https://immuniweb.com/websec/
Overview of properties: http://toolbar.netcraft.com/site_report
Server analysis, detailed: https://check-your-website.server-daten.de
Debug DNSSEC: http://dnssec-debugger.verisignlabs.com
HTTP/2 test: https://tools.keycdn.com/http2-test
Test host reachability: https://nat64check.org
Test local IPv6 capability: http://ipv6-test.com
Find hosting data: https://dnsquery.org
List shared server URLs: https://viewdns.info/reverseip
Analyze IP ownership: http://whois.domaintools.com
Search geographic location: https://www.ultratools.com/tools/geoIpResult
Describes three locations: https://check-host.net/ip-info
Find Subdomains (A records): https://hackertarget.com/find-dns-host-records
Analyze type of application: https://www.wappalyzer.com/download

Domain Name System (DNS):

Check on DNS setup:
http://www.viewdns.info / https://intodns.com / http://bwachter.lart.info/tools/dig.cgi
For an ‘AAAA’ record for IPv6, a data center must be up-to-date.
A ‘TLSA’ record for DANE ensures secure e-mail transport, and in the future for an URL.
A ‘CAA’ record protects against a different SSL certificate provider than set in the DNS.

Some background information:

HSTS restricts to https: https://en.wikipedia.org/wiki/HTTP_Strict_Transport_Security
HTTP/2 webpage traffic optimization: https://en.wikipedia.org/wiki/HTTP/2
SNI same owner of (server) domain: https://en.wikipedia.org/wiki/Server_Name_Indication