Why Tracking Your DNS History Is Important
If you have ever published a blog post and then got so much flack for it you ended up taking it down – and you still think this would make the problem go away, think again. If your readers have your blog on their RSS feed and click on its link, they’ll still be very likely to be able to read a cached version of it.
The same is unfortunately true for domains. Every change a domain goes through is recorded on its historical WHOIS record, made possible by the introduction of passive Domain Name System (DNS) — a means to find out any modification made at some point in time to a specific domain.