The Domain Name System (DNS) is one of the main systems that keeps the internet working, helping your device find the correct online service whenever you enter a website address, open an app or send an email.
Without this system, people would need to remember a long numerical address for every website they wanted to visit; instead, you can type a clear name such as tasjeel.ae into a web browser, and the directory finds the server linked to it.
This guide explains what DNS is, how a lookup works and why several types of server are involved. It also covers records, caching, security and encrypted requests.
What does DNS mean?
DNS stands for Domain Name System, a distributed directory that connects a human-readable domain name to the technical information computers use to communicate.
Domain Name System
The domain name system DNS process is often compared with looking up a contact in your phone: you select a person by name instead of remembering their number, just as you enter a domain rather than a server address.
Internet Protocol IP addresses
Computers exchange data through Internet Protocol IP addresses; an IPv4 address might look like 192.0.2.1, while an IPv6 address is longer and can contain both numbers and letters, so neither format is convenient for most people.
DNS links names and addresses, making the internet easier to use. As ICANN’s explanation of the Domain Name System notes, a device can look up a domain and find its IP address. DNS records can also identify mail servers, verify domain ownership and support email security.
Why is the Domain Name System important?
DNS provides a stable naming layer between a user and an online service, allowing a business to retain the same domain after changing its hosting provider or server IP address; its records point towards the new service while customers keep using the same web and email addresses.
DNS supports a huge global network without one central directory. Responsibility is shared across the DNS hierarchy, helping it scale while organisations manage their own zones.
For a website owner, accurate DNS settings are essential because a wrong record can stop a site loading or prevent email reaching an inbox; when connecting a domain to new web hosting, the provider will normally give you the required values.
How does DNS work?
The full process, known as domain name resolution, starts when a person enters a domain into a browser or an application needs to reach an online service.
First, the device and browser check their caches for a recent answer. If a valid result is stored, the device can use it at once.
If there is no cached result, the device sends a request to a DNS resolver, which for many households and offices is supplied by their internet service providers ISPs, although public and private alternatives are available.
The resolver checks its cache and, if needed, asks other DNS servers in a set order before returning the answer to the device, allowing the browser to contact the web server.
The exchange normally happens in a fraction of a second and is rarely visible, but many online activities depend upon successful DNS queries.
What happens during a DNS lookup?
A fresh lookup moves through a hierarchy; no single server has to store every domain on the internet.
- The device checks its cache: the browser, operating system or local network may already have an unexpired result
- The device contacts a recursive resolver: this server accepts the request and works to produce a final answer
- The resolver asks a root name server: the root server directs it towards the correct top-level domain server
- The resolver asks a TLD name server: this server identifies the authoritative name servers for the requested domain
- The resolver asks an authoritative server: it returns the relevant record, such as the domain’s IP address
- The answer returns to the device: the resolver sends the result back and normally caches it for later requests
- The browser connects to the service: it uses the answer to contact the website’s server
Caching often removes some of these steps. This reduces DNS lookups, cuts DNS traffic and helps pages begin loading more quickly.
Which DNS servers are involved?
Several types of server may take part in a lookup. Each has a separate role.
Recursive resolvers
DNS resolvers receive requests and find the response. A resolver is “recursive” because it follows referrals until it has an answer or error to return.
The terms recursive resolvers and recursive DNS servers often mean the same thing; because they cache answers, a popular record may be returned without a new journey through the hierarchy.
Root name servers
Root name servers sit at the top of public DNS and, rather than providing a website’s IP address, point the resolver towards the relevant top-level domain servers.
TLD name servers
Top level domains are the final section of a domain, such as .com, .org or .ae; the phrase top level domain TLD refers to this part of the name and its place in the hierarchy.
A TLD name server provides the domain’s authoritative name servers. A request for a .ae address, for example, is directed through the infrastructure for that country-code TLD.
Authoritative name servers
Authoritative name servers hold the data for a domain or zone. They can answer for records they manage without seeking them elsewhere.
Most domains use more than one server for resilience. The terms authoritative name servers and authoritative DNS servers describe the same role.
Cloudflare provides a useful overview of the four main server types and how they work together during resolution.
What is a query?
A query asks for information about a name and record type, while the response can contain the requested data, a referral or an error.
Not all DNS queries work in the same way. A recursive query asks for a final answer. An iterative query may receive a referral to another server. A non-recursive query is answered directly because the server is authoritative or has cached the result.
Traditional DNS protocols commonly use UDP on port 53. TCP can handle larger responses and certain server-to-server tasks. Encrypted options use other methods.
What are the main DNS record types?
A domain’s zone contains records that control how it works. Each DNS resource record has a type, name, value and time to live. The time to live, or TTL, tells caches how long they may keep the result.
Common record types include:
- A record: Connects a name to an IPv4 address
- AAAA record: Connects a name to an IPv6 address
- CNAME record: Makes one name an alias of another hostname
- MX record: Identifies the mail servers that receive email for the domain
- TXT record: Stores text used for verification and policies such as SPF, DKIM or DMARC
- NS record: Identifies the authoritative name servers for a zone
- SOA record: Provides core administrative information about the zone
- SRV record: Identifies a host and port for a particular service
- PTR record: Maps an IP address back to a hostname in a reverse lookup
Cloudflare’s guide to common record types gives further examples of the information each record can hold.
Change records with care. An A or CNAME error can misdirect visitors, while a wrong MX record can interrupt email. A long TTL may leave an old setting in caches after an update.
What are caching and propagation?
Caching improves speed and reduces work because browsers, operating systems and resolvers may keep an answer until its TTL expires.
After a change, some users may still receive the old value during a delay often called propagation; in most cases, the change is not travelling between servers, but separate caches are expiring at different times.
The TTL affects the delay. A lower value tells resolvers to refresh sooner, which can help before a migration but creates more DNS traffic. A higher TTL cuts repeat requests but may make updates take longer to appear.
Plan important changes. Lower the TTL before a move, check the new setup and keep the former service running during the transition where possible.
How can you find a domain’s settings?
You can inspect public data with a lookup tool such as DomainTools, which can show registration data and a domain’s name servers; WHOIS and the naming system are related but different because WHOIS concerns registration, while the latter controls how services are found.
You can also use a domain or hosting control panel, where the relevant area may be called zone management, zone editor or name servers.
Tools such as nslookup and dig can request a record type and show the response, while web-based lookup tools provide a simpler option.
To change the resolver used by your device, follow the instructions for its operating system or router. This PCMag guide to changing a resolver covers the process. Do not change a domain’s authoritative servers when you only want a different resolver; they are separate settings.
What are DNS over TLS and DNS over HTTPS?
Traditional requests lack transport encryption. Someone observing the network path may see or alter them. Two newer approaches protect the connection between a device and a compatible resolver.
DNS over TLS DoT sends messages through a Transport Layer Security connection. IETF RFC 7858 describes TLS as a way to reduce eavesdropping and tampering with queries.
DNS over HTTPS DoH sends queries through HTTPS, the secure transport used for web traffic. It is defined in IETF RFC 8484. Google also offers a practical secure resolver overview.
DoT and DoH encrypt this part of the route, but they are not a VPN and do not make browsing anonymous. The resolver still handles the requests. DNSSEC is a separate system used to validate signed records.
What is a DNS service?
A DNS service may provide recursive resolution for internet users or authoritative hosting for domain owners. Recursive services answer devices, while authoritative services publish a domain’s records. When choosing a provider, consider reliability, support, account security, privacy and support for encrypted protocols.
Common problems and checks
A naming or resolution issue can affect a website even when its host is working. Common causes include:
- A missing or incorrect A, AAAA or CNAME record
- Name servers that do not match those assigned by the provider
- Old answers remaining in a browser, device or resolver cache
- An MX record pointing to the wrong email system
- A typing error or DNSSEC details that do not match the active setup
- A recent update made before the old record’s TTL has expired
Check whether the fault affects one device, one network or everyone. Try another connection and more than one resolver. Confirm the domain is active, then compare its name servers and records with the provider’s required values.
Avoid several changes at once. Save the old values before editing, then allow for caching when you test the result.
Frequently asked questions
Is it the same as a domain name?
No. A domain name is the readable address people use. The Domain Name System stores and finds the technical information connected with it.
Is it the same as web hosting?
No. Web hosting stores and serves website files, while the naming system helps a device find the correct server. A working website normally needs both services to be configured correctly.
Why do changes appear at different times?
Resolvers may keep an older answer until its TTL expires. Different users can therefore receive different answers for a short period after a change.
Can this process affect website speed?
Yes, but it is only one part of performance. A fast, reliable resolver can reduce the time required to start a new connection. Website code, images, hosting and network distance usually have a much larger effect on the full loading time.
Are encrypted requests automatically enabled?
Not always. Support depends on the device, browser, network policy and resolver. Some modern systems enable secure resolution automatically or allow the user to choose it in network or browser settings.
A simpler way to navigate the internet
The system turns memorable names into the information needed to reach websites, email and other services. A resolver handles the request, the hierarchy directs it, and an authoritative server supplies the record.
For users, this happens quietly in the background. For website owners, the basics help with hosting, email and fault finding. Keep records accurate, protect the domain account and plan changes around caching and TTL values.
For more guides about domains, hosting and getting online, visit the Tasjeel blog. For a deeper reference, explore the Domain Name System article on Wikipedia.
