Free online network tools:
1) Central Ops .net - This site is a collection of Internet utilities developed by Hexillion.
2) Network-Tools.com - One of the good site with lots of utilities.
3) IP Checking - Good one for IP checks and geolocation
4) DNS Watch - DNS lookup and performance monitoring
5) Domain To0ls - WHOIS lookup
6) AllWHOIS.COM - Allwhois™, a free service provided by MarkMonitor, is the most complete whois service on the Internet.
7) MXTOOLBOX - MX lookup, RDNS, SPF headers, Blacklist, Port scan and much more..
8.) InToDNS - A light weight, easy DNS and Mail server check website.
9) What is my IP - Check your current IP address.
10) ViewMyIP - Another simple website with no scripts to check your current IP address.
1) whatwpthemeisthat.com - To check WordPress theme used by the website.