DNS Explained, How Domain Names Become Addresses
DNS is the phone book of the internet. You type example.com, and DNS finds the number behind it. Without DNS you’d have to memorize long strings of digits for every site you visit.
The record types you’ll actually use
- A, points a domain to an IPv4 address
- AAAA, same idea, for IPv6
- MX, tells the world which servers handle email for a domain
- NS, names the authoritative name servers
- TXT, freeform text, mostly used for SPF, DKIM, and domain verification
- CNAME, an alias pointing one name at another
- SOA, the zone’s administrative metadata
Checking records yourself
The fastest way is a DNS lookup. On the command line you’d reach for dig on Linux/macOS or nslookup on Windows. Both do the same thing: ask a resolver for specific record types and print what comes back.
Why records change slowly
Most records carry a TTL (time to live) in seconds. Your device and routers cache answers until that timer runs out, which is why DNS changes can take minutes to a day to fully propagate.
Related tools
Try the live DNS lookup, then learn how your IP and location connect to those records.
Further reading
A worked example
Say you type shop.example.com into your browser. Your device asks a resolver, usually one provided by your ISP. The resolver checks its cache first. If it has no fresh answer, it walks up the chain: root servers, then the .com TLD servers, then the authoritative name servers for example.com. The final answer, often something like 203.0.113.44, gets cached according to its TTL, often 300 seconds. You can see this whole answer by running a lookup in the tool at /dns.
Common problems and what DNS reveals
- Site does not load but ping works: often a missing A record or wrong name server.
- Email goes to spam or fails SPF checks: usually a broken or missing TXT record on the domain.
- Intermittent 502 errors: a low TTL on the wrong record type can send traffic to an old server.
- Slow first page load: a slow recursive resolver can add hundreds of milliseconds before any content starts.
FAQ
How long do DNS changes take to propagate?
It depends on the old TTL. If the old record had a 24 hour TTL, some resolvers can keep serving it for up to a day. Lowering the TTL before a migration makes the cutover much faster.
Is DNS the same as hosting?
No. DNS only tells the world where your domain points. Hosting is the actual server that serves your website. People often confuse them because changing name servers or A records feels like moving the site.
Can DNS be hacked?
DNS hijacking and cache poisoning are real threats, which is why standards like DNSSEC and encrypted resolvers such as DoH and DoT exist. Choosing a reputable resolver, like the ones compared in the DNS speed check, reduces your exposure.
What happens if my DNS server is down?
Your device will usually fail over to a backup resolver if one is configured. On most home setups there is no backup, so every lookup fails and the internet appears completely down even though the connection is fine.