The domain name system (DNS) translates user-friendly names to IP addresses and is used by web browsers to find websites. ICANN oversees the distribution of domain names and IP addresses worldwide. Local networks can have their own DNS systems, and alternative DNS root systems pose a risk to Internet stability and security.
Domain name systems are distributed database systems that translate between user-friendly names and numeric Internet Protocol (IP) addresses. The most common domain name system is the one used by the entire Internet. It’s called “the domain name system” and is also known by the acronym DNS. Its database is globally distributed across many thousands of domain name servers on the Internet. It is frequently used by web browsers connected to the Internet to determine the IP addresses of websites to visit.
Internet domain name systems can be thought of as huge online telephone directories for websites. Anywhere in the world, anyone can type a Universal Resource Locator (URL) into a Web browser and end up on that site. DNS allows users to refer to a website simply by using its domain name. That name remains the same despite the Internet’s transition from IP version 4 addresses to longer IP version 6 addresses.
The first domain name systems and DNS servers were developed in the early 1980s as the Internet grew rapidly in size. The original protocols were published by the Internet Engineering Task Force (IETF) in Request For Comments (RFC) 882 and RFC 883. The software and protocols have been reviewed many times, mainly for security reasons.
For domain name systems to be truly useful, each name must resolve to a unique IP address. In 1998, the Internet Corporation for Assigned Names and Numbers (ICANN) was formed to handle this process. ICANN is a non-profit entity that oversees the distribution of domain names and IP addresses worldwide. It also handles the assignment of specific ports and parameter values for the many Internet protocols, including DNS. The 13 mirrored servers that make up the Internet’s DNS root are also coordinated by ICANN.
Internet root servers include DNS server addresses for all top-level domains, such as .com and .org. Each top-level server contains a DNS database of all names and addresses in that domain. Portions of these DNS databases are also cached by thousands of DNS resolvers located at Internet Service Providers. This lightens much of the traffic load that would otherwise be placed on top-tier servers. Individual web browsers also include caches of visited domains to make site searches as fast as possible.
Local networks isolated from the Internet can use their own domain name systems. These only translate names and addresses that are on the local network. They often use DNS management software and protocols that are similar or identical to those used by the implementation of the Internet. There are a few alternative DNS root systems online that are duplicates of the existing Internet structure, but include multiple names. These pose a risk to Internet stability and security because a domain name could be resolved to different addresses by different systems.
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