DNS

You can name a restaurant anything. The city still needs a street.

DNS is the clerk who files that street next to the name. Computers do not browse yourapp.com. They travel to a number — an IP. You buy the name so judges can type something human. You still have to tell the clerk which building the name opens.

Buying demo-squad.com does nothing by itself. That is a sign with no door behind it. Pointing is the other half: write down "this name goes to Vercel" or "this name goes to Cloudflare." The deploy already put a building on the internet. DNS is how the painted sign leads there.

Two stickers you will actually see

• An A record says "this name lives at this number." Straight line.
• A CNAME says "treat this name like that other name." A nickname. Most hackathon custom domains are this: www pointing at whatever the host handed you.

You do not need to memorize the form. When the host says "add these DNS records," they are handing you the street.

Changes spread. The clerk in your city updates first. A judge across the room may still have yesterday's street for an hour. That lag is why "it loads for me" and "blank for them" can both be true after you flip a domain. It is also why people shrug and say it is probably DNS. The app is up. The sign is lying, or still drying.

If localhost worked and the custom domain is a white screen, stop rewriting the frontend. Argue with the clerk.

What this unlocks

A deploy gives you a rented URL. DNS is how that URL becomes a name you chose. Until the clerk files it, you have a working kitchen with a sign in the wrong city. After, judges type something you can say out loud.

The cloud host will give you the street. You just have to write it down.