The problem DNS solves
Computers on the internet communicate by sending data to IP addresses — numerical identifiers like 142.250.80.46. Every web server, every mail server, every CDN node has an IP address. Humans, however, are terrible at memorising sequences of numbers. We remember google.com, not 142.250.80.46. DNS — the Domain Name System — is the translation layer between these two worlds. It converts human-readable domain names into the IP addresses computers actually use.
Without DNS, you would need to manually look up the IP address for every website you wanted to visit. DNS runs invisibly in the background, completing this lookup in 20–120 milliseconds, on every single page load. It is one of the most quietly essential pieces of infrastructure on the internet.
The lookup process — step by step
When you type a URL into your browser, this is exactly what happens:
Step 1: Local cache check. Your computer first checks its own DNS cache — a short-term memory of recent lookups. If you visited google.com five minutes ago, the IP is probably still cached and the lookup completes instantly, in microseconds.
Step 2: Ask your resolver. If the cache is cold, your computer asks its configured DNS resolver. This is usually your ISP's resolver, though many people configure Google (8.8.8.8), Cloudflare (1.1.1.1), or another third-party resolver. The resolver also has a cache — popular domains like google.com are almost always cached here.
Step 3: Root nameservers. If the resolver does not have it cached, it asks one of the 13 root nameserver clusters distributed worldwide. The root servers do not know the final IP address — they only know which nameservers handle each top-level domain. A query for google.com gets pointed to the .com TLD nameservers.
Step 4: TLD nameservers. The .com TLD nameservers know which nameservers are authoritative for google.com specifically. They return that information.
Step 5: Authoritative nameserver. Finally, the resolver asks Google's own nameservers — the authoritative source for google.com. These return the actual IP address. The resolver caches this result and returns it to your computer. The whole round trip from step 2 to step 5 typically takes 20–80 milliseconds.
DNS record types you actually need to know
DNS is not just "domain → IP." There are several record types, each serving a specific purpose:
A record — the basic one: maps a domain name to an IPv4 address. example.com → 93.184.216.34. Every domain needs at least one A record to be accessible via a browser.
AAAA record — same as A, but for IPv6 addresses (the longer format like 2001:4860:4860::8888). Most modern hosting adds these alongside A records.
CNAME record — an alias that points one domain to another. www.example.com → example.com. The browser then resolves the target domain. CNAMEs cannot coexist with other records on the same name, which causes issues at the zone apex (root domain) — something called "CNAME flattening" by providers like Cloudflare solves this.
MX record — specifies which mail server handles email for a domain. When someone emails [email protected], the sending server looks up the MX records for example.com to know where to deliver the message.
TXT record — stores arbitrary text. Used for: SPF records (email authentication), DKIM keys (email signing), domain ownership verification (Google Search Console, Cloudflare, etc.), and DMARC policies.
NS record — specifies which nameservers are authoritative for a domain. These are set at your domain registrar and point to your DNS provider.
TTL — why DNS changes take time to propagate
Every DNS record has a TTL (Time to Live) — a number in seconds that tells resolvers how long to cache it. A TTL of 3600 means the record is cached for one hour. During that hour, every resolver that cached the old record will keep using it, even if you changed it five minutes ago.
This is why DNS propagation takes time — often 1–48 hours. When you move a website to a new host and update the A records, visitors whose ISP resolver cached the old record will continue reaching the old server until their cache expires. You cannot force this to happen faster — you can only wait for TTLs to expire.
The practical implication: if you know you are going to change hosting, lower your TTL to 300 (5 minutes) a day or two before making the switch. This dramatically reduces propagation time. After the switch, you can raise it back to 3600 or higher.
How my IP Lookup tool connects to DNS
When you look up your IP address with my tool, you see the IP, city, ISP, and ASN. The ASN (Autonomous System Number) is particularly interesting for understanding DNS: large ISPs and cloud providers run their own DNS resolvers inside their AS, and your DNS queries typically go to a resolver within the same network, which is why your DNS responses can differ from what someone on a different ISP or in a different country would see for the same domain.