Definition: DNS Spoofing is an attack method that is used by crackers to re-direct a request for a specific Internet site to another computer by means of fooling or "hi-jacking" the Domain Name Service session. A malicious user, in a "spoof", able to “convince” your computer that the attacker’s site is to be trusted and in fact is the site you requested. A cracker would be capable of gaining access to all of the information from the trusted site. The Domain Name Service uses the UDP protocol which, unfortunately, fails to provide for authentication services. Without authentication identities can't be verified.
Its Relevance: A Domain Name Service exploit can be particularly harmful and measures must be taken to avoid falling victim to such an attack. Infrastructure owners could avoid name service hijacking by encrypting traffic. By default a robust form of “authentication” (knowing the key) is put into place.