What is DHCP?
Dynamic Host Configuration Protocol, told as a story about the desk that lends number tags to newcomers in the hallway.
A newcomer has no number tag.Without a tag (an address), nobody in the hallway can find you. This comes right after the gatekeeper at the socket.
Hand-written tags collide.Two number 7s and letters go astray. With a hundred, nobody knows who has what.
DHCP is the desk that lends out spare number tags.'Number 23, until tonight.' It also tells you where the directory and the gate are.
Renew as time passes; give it back when you leave.Halfway through, 'I'll keep it'; when you leave, the tag returns. That's why the desk never runs dry.
A fake desk handing out tags is trouble.Anyone can open a desk, so a thief who writes "the directory is over there" sends everyone to a fake directory. Which is why the gatekeeper at the socket checks desks too.
DHCP = the desk that lends a newcomer a spare number tag (address) until tonight, and tells them where the directory and the gate are.
Dynamic Host Configuration Protocol. Your home router is this desk. The tag is an IP address, the directory is DNS, the gate is the gateway.
When grown-ups say it
- IP address
- The number tag. The number the hallway finds me by. → the wall with many doors
- Address pool
- The desk's bundle of spare tags. Run out, and newcomers get nothing.
- Lease
- Until tonight. The tag is a loan, with a term.
- Renewal
- I'll keep it. Halfway through the term, tell the desk again.
- Gateway
- The gate. The door you use to go out — written on the note. → the wall story
- DNS server
- The directory. Turns names into addresses — also on the note. → the town directory
- Reservation · static address
- A reserved seat. For printers and desks that must keep the same number.
- Rogue DHCP
- A desk opened by a thief. Hands out a fake directory address. → the gatekeeper at every socket stops it