DNS blocking

Common card · No. 392799

Domain Name System blocking, or DNS blocking / filtering, is a strategy for making it difficult for users to locate specific domains or websites on the Internet. It was first introduced in 1997 as a means to block spam email from known malicious IP addresses. DNS blocking can also be applied for outgoing requests as well. Instead of returning the valid IP address of a requested site (for example, instead of 198.35.26.96 being returned by the DNS when "www.wikipedia.org" is entered into a browser, if this IP were on a block list, the DNS might reply that the domain is unknown or with a different IP address that directs to a site with a page stating that the requested domain is not permitted). The latter case where the user is redirected to another destination would be considered DNS Spoofing, otherwise known as "DNS Poisoning". DNS blocking can be applied to individual domain names or all their sub domains. Another form of content blocking is IP address blocking, where servers IP address...

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