DNS and Search Engine Ranking

What is a DNS ?
According to DNS.net, "The Domain Name System (abbreviated DNS) is an Internet directory service. DNS is how domain names are translated into IP addresses, and DNS also controls email delivery. If your computer cannot access DNS, your web browser will not be able to find web sites, and you will not be able to receive or send email.

What does DNS contains?
The DNS system consists of three components: DNS data (called resource records), servers (called name servers), and Internet protocols for fetching data from the servers.
The billions of resource records in the DNS are split into millions of files called zones. Zones are kept on authoritative servers distributed all over the Internet, which answer queries based on the resource records stored in the zones they have copies of. Caching servers ask other servers for information and cache any replies. Most name servers are authoritative for some zones and perform a caching function for all other DNS information. Large name servers are often authoritative for tens of thousands of zones, but most name servers are authoritative for just a few zones. "

Bill Gates has once termed DNS as Short for digital nervous system while explaining the relationship in a hosting network.

For example, the domain name of India's premium hosting provider http://www.newfunda.com/ might translate to anything like 198.x.x.x and x can be anything depending upon your hosting, shared or dedicated.

Does change in DNS affects Google Ranking?
Its hard to judge in general, but if we consider our experience, then yes it affects (mostly lowers down in number of pages indexed for a particular period of time)
As Google is also a Domain Registrar himself, it has access to all the DNS entries and WHOIS data related to each domain.
Google's Patent Claims as:
"The method of claim 1, wherein the one or more types of history data includes domain-related information corresponding to domains associated with documents; and wherein the generating a score includes: analyzing domain-related information corresponding to adomain associated with the document over time, and scoring the document based, at least in part, on a result of the analyzing."