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Google, a major provider of services on the Internet, experimented with using a type of DNS allowlisting on a per-ISP basis to prevent this [9] [10] until the World IPv6 Launch. In the DNS allowlisting approach, ISPs are determined from DNS lookup source IP addresses by correlating them with network prefixes derived from routing tables .
A reverse DNS lookup is a query of the DNS for domain names when the IP address is known. Multiple domain names may be associated with an IP address. The DNS stores IP addresses in the form of domain names as specially formatted names in pointer (PTR) records within the infrastructure top-level domain arpa. For IPv4, the domain is in-addr.arpa.
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. [1] DNS blocking can also be applied for outgoing requests as well.
For example, to do a reverse lookup of the IP address 8.8.4.4 the PTR record for the domain name 4.4.8.8.in-addr.arpa would be looked up, and found to point to dns.google. If the A record for dns.google in turn pointed back to 8.8.4.4 then it would be said to be forward-confirmed.
In addition, different answers may be provided to DNS clients based on the clients' geographic location, as determined by their IP address . The most practical way to manage such critical Internet infrastructure has been to rely on databases and complex DNS management software to ensure homogeneity and avoid single points of deployment errors.
Dynamic IP addresses present a problem if the customer wants to provide a service to other users on the Internet, such as a web service. As the IP address may change frequently, corresponding domain names must be quickly re-mapped in the DNS, to maintain accessibility using a well-known URL.
Internet protocols use IP addresses for communications, but these are not easy for humans to use; IPv6 in particular uses very long strings of digits that are not easily entered manually. To address this issue, the internet has long used DNS, which allows human-readable names to be associated with IP addresses, and includes code for looking up ...
DNS hijacking, DNS poisoning, or DNS redirection is the practice of subverting the resolution of Domain Name System (DNS) queries. [1] This can be achieved by malware that overrides a computer's TCP/IP configuration to point at a rogue DNS server under the control of an attacker, or through modifying the behaviour of a trusted DNS server so that it does not comply with internet standards.