There are many online tools, services and websites which provides a domain name DNS, MX records, CNAME, txt and A records information etc. Along with this registrant information i.e. whois data for a domain is also available on such sites. Other then these options, one can search for reverse IP lookup, other websites on same IP to know about neighbourhood websites etc.
Some sites that provide this data are:
- who.is
- whois.sc
- whois.net