DNS stands for Domain Name System. It lets your device look up information about a domain name, including the IP addresses used to reach a website. You remember a name such as example.com; DNS helps software discover where to send its connection request.
The useful distinction is between finding a destination and communicating with it. DNS handles the lookup. Loading the page involves additional steps, so a working DNS answer does not guarantee that a website will open.
How does a domain name become an IP address?
A domain name is a readable identifier. An IP address identifies a network destination that computers can use when sending packets. DNS connects those two kinds of information through records. A name can have several addresses, and several names can lead to the same address.
DNS is distributed rather than stored in one enormous master directory. Organizations manage different portions of the namespace, called zones, and servers refer questions onward when necessary. This division of responsibility is central to the design described in RFC 1034, the DNS concepts standard.
For a web address such as https://example.com/guides, the hostname is example.com. The https part identifies the connection scheme, and /guides identifies a resource on the site. DNS does not look up that entire web address as one string. Keeping these pieces separate makes error messages easier to interpret.
What do recursive and authoritative servers do?
A recursive resolver works on the client’s behalf to obtain an answer. Your device may use a resolver supplied through your home network, internet provider or organization. If a usable answer is already cached, the resolver can return it without repeating the full search.
When it needs to follow the hierarchy, the resolver can ask a root server where to find the relevant top-level domain, such as .com. The top-level-domain server then directs it toward the domain’s authoritative nameservers. An authoritative server supplies records for the zone it serves. Additional lookups may be needed for aliases or delegated subdomains.
Think of the resolver as doing the asking and the authoritative service as maintaining the relevant published records. A cached response from a resolver is normal; “non-authoritative answer” is not, by itself, an error. Cloudflare’s DNS overview explains these roles and the lookup sequence.
Why are DNS answers cached, and what is TTL?
Caching keeps a temporary copy of an answer so the same question can be answered quickly. It also reduces repeated work for DNS servers. Cached information can exist at several points, including the device and the recursive resolver.
TTL means time to live. It tells a cache how long a record may normally be reused before a fresh lookup is needed. DNS TTL values are expressed in seconds: 300 seconds is five minutes, while 3,600 seconds is one hour.
If a site owner changes an address, someone with an unexpired cached answer may still reach the old destination. Different caches expire at different times, so there is no single global refresh button. Lowering a TTL after an old answer has already been cached does not retroactively shorten that cached answer’s original lifetime. See Cloudflare’s TTL documentation for the caching trade-off.
Which DNS records should beginners recognize?
Records answer different questions. A records supply IPv4 addresses; AAAA records supply IPv6 addresses. A CNAME makes one name an alias of another name, which may then require another lookup. It does not perform a browser redirect to a different page.
MX records identify mail servers for a domain. NS records identify authoritative nameservers. TXT records hold text that services can use for purposes such as domain verification and email policy. You do not need to memorize every type, but you do need to ask for the right one when investigating a problem. Cloudflare documents these record types in more detail.
Is DNS the same as hosting or HTTPS?
Web hosting provides the systems that serve a site’s content. DNS helps locate an address associated with the site. HTTPS protects the browser’s connection using TLS and certificate checks. These services cooperate, but each can fail independently. Mozilla’s HTTP overview describes the request-and-response stage that follows locating a server.
For example, an address lookup can succeed while the web server is unavailable. A page can also have a certificate problem even when its DNS records are correct. Treat a certificate warning as a security issue to investigate, not as something to bypass because a DNS lookup returned an address.
How can you check DNS safely?
Start by checking the spelling of the hostname and noting the exact error. See whether the problem affects one website or several. On a work or school device, record what you observe and contact the administrator rather than replacing managed DNS settings or disabling protective software.
On Windows, open Command Prompt and run nslookup example.com. This requests a lookup through the tool’s default DNS server. Read the server information separately from the answer for example.com. Microsoft’s nslookup documentation explains the command and its diagnostic output.
On a Mac or Linux system with dig available, run dig example.com A for IPv4 records or dig example.com AAAA for IPv6 records. These are read-only queries; they do not edit DNS records or network settings. The BIND dig manual documents query types and response details.
A timeout means no timely answer arrived, not necessarily that the domain is missing. NXDOMAIN reports that the queried name does not exist in the DNS response you received. Save the hostname, time and output for support. Avoid sharing internal hostnames or network details publicly. DNS results are useful evidence, but interpreting them alongside the browser error is more reliable than changing settings at random.
Further learning
For an optional introduction to the wider subject, browse beginner computer-networking books on Amazon. No purchase is needed to run the read-only checks above.
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