When you type a domain like developk.kr into a browser, you're actually connecting to the IP address of a server hiding behind that name. This article covers how a domain gets translated into an IP, why a single domain can return several different IPs, and how to check it yourself.
How a domain becomes an IP
A domain name is just a human-friendly alias — actual internet communication happens over IP addresses. The system that connects the two is DNS (Domain Name System). When a browser tries to reach a domain, it first asks a DNS resolver (usually your ISP's or a public one like 1.1.1.1 or 8.8.8.8), "what's the IP for this domain?" The records it looks up are the A record (an IPv4 address) and the AAAA record (an IPv6 address). An A record holds a 32-bit IPv4 address like 192.0.2.10, while an AAAA record holds a 128-bit IPv6 address like 2001:db8::1. Once a domain owner publishes these records on their DNS servers, anyone anywhere in the world can reach the same server (or set of servers) through that domain name.
Why a domain can return multiple IPs
It's common to look up a domain and get back more than one IP address. That's not a bug — it's usually intentional. There are two main reasons. The first is load balancing: high-traffic services run multiple servers and register all of their IPs under the same domain, spreading requests across them (round-robin DNS). Different clients, or even different requests from the same client, can get different IPs, which evens out the load. The second is CDN (content delivery network) usage. Services like Cloudflare or Akamai return the IP of whichever edge server is geographically closest to the requester, so a lookup from Korea and a lookup from the US may return different — but equally correct — IPs. Multiple IPs are also commonly registered for failover, so traffic can shift automatically if one server goes down.
Checking it yourself
You can check a domain's IP from the command line. On macOS or Linux, running dig developk.kr A lists the registered IPv4 addresses in the ANSWER section; on Windows, nslookup developk.kr gives similar output. The downside is that these commands return plain text and make it awkward to compare IPv6 alongside multiple records at once. If you just want to type in a domain and instantly see its IPv4 and IPv6 addresses side by side, doing it in the browser without installing anything is much faster.
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How to Find a Domain's IP Address — Find the real server IP a domain points to