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Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →The Domain Name System (DNS) is the distributed, hierarchical system that lets people and applications use domain names to request information associated with those names. It can provide host addresses, mail-related information, and other data; it is not simply a one-step conversion of every name into an IP address.
What does DNS stand for?
DNS stands for Domain Name System. It organizes names and associated information in a hierarchy, then enables software called resolvers to find the requested information across servers that hold different parts of that hierarchy.
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Why does DNS exist?
People can use memorable names rather than having to remember numerical IP addresses. For example, ICANN uses whois.icann.org to illustrate the levels of a name: org is the top-level domain, icann is the second-level label, and whois is a label beneath it. A DNS query can ask for different kinds of information associated with a name, not just an address.
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How is DNS organized?
RFC 1034 describes the DNS name space as a tree. Its information is divided among name servers and organized into zones, which are portions of that space for which authoritative information is maintained.
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- Domain name space: the hierarchy of names and associated resource information.
- Resource record: a data item associated with a name. The query type indicates what kind of information is requested.
- Name server: a server program that holds DNS information and can answer from its data or refer a query onward.
- Zone: a unit of authoritative DNS information served by one or more name servers.
- Root: the top of the public DNS hierarchy, which directs resolution toward top-level domains.
What happens during a DNS lookup?
In a simplified lookup, a resolver seeks the requested information and follows referrals through the hierarchy toward servers authoritative for the relevant zone. ICANN describes iterative resolution as beginning at the root zone: root service points toward the relevant top-level domain, which can point toward the domain’s authoritative name servers, which can answer for names in their zone.
- The application requests information. A browser or other application asks a resolver for a particular record associated with a name.
- The resolver checks available information. It may be able to answer using cached data from an earlier lookup. If it cannot, it queries DNS servers and follows referrals.
- The hierarchy directs the query. In the simplified path, root and top-level-domain servers direct the resolver toward the appropriate authoritative servers.
- An authoritative server responds. A server authoritative for the relevant zone provides the requested information, or indicates that the requested name or record is not available there.
- The resolver returns the result. It gives the answer to the client; cached results can help avoid repeating the full lookup while they remain usable.
This is a conceptual path, not a guarantee that every lookup sends queries to each level. Actual behavior depends on the resolver’s configuration, cache contents, query type, and protocol extensions. RFC 1034 and RFC 1035 provide the foundational technical descriptions; ICANN’s resolver and root explanations describe the hierarchy in accessible terms.
What is the difference between a resolver and an authoritative name server?
A resolver works on behalf of a client to obtain DNS information. It may use cached answers or query servers and follow referrals. An authoritative name server holds the authoritative information for a zone and answers from that portion of the name space. These are different roles: one seeks an answer, while the other serves authoritative data for its zone.
Is DNS the same as registering a domain?
No. DNS is the naming and information system; a domain name is a name within that system. A registrar may help someone register a domain, and a DNS hosting service may operate name servers for it, but those commercial services are not DNS itself. Registration and DNS hosting are related ways people manage names and their records.
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