Below are some of our favorite hosting tools:
http://intodns.com/ – IntoDNS checks the health and configuration and provides DNS report and mail servers report. And provides suggestions to fix and improve them, with references to protocols’ official documentation.
http://mxtoolbox.com/ – This test will list MX records for a domain in priority order. The MX lookup is done directly against the domain’s authoritative name server, so changes to MX Records should show up instantly. You may also check each MX record (IP Address) against 105 DNS based blacklists . (Commonly called RBLs, DNSBLs)
http://www.yougetsignal.com/ – Port FW tester, also has reverse IP domain check to see other sites on a server. Other tools include visual trace route, what is my IP.
https://who.is/ WHOIS Search