The naming problem
People remember names. Networks need destinations.
When you visit a website, you usually start with a name such as fusingbits.com. A network cannot deliver traffic using that human-friendly label alone. It needs an address that identifies where the traffic should go.
That creates a translation problem: how do we turn a name into an address without making people memorize numbers?
Compare the cases
Different ways to find a device or service
PAN · Bluetooth
Nearby devices advertise their identity or services. Pairing and Bluetooth discovery usually happen without DNS.
LAN · Direct address
If a device already knows a local IPv4 address, ARP can find the corresponding MAC address on the local link. DHCP may have supplied the IP configuration first.
LAN · Local name
A local service such as a printer can be announced or resolved with mDNS, often using a name ending in .local, without using public DNS.
Internet · Domain name
For a name such as fusingbits.com, DNS can return an IP address. Routing and the connection then carry the traffic to that destination.
Build the model
Three useful layers
Name
A label people can read and share, such as fusingbits.com.
Lookup
DNS looks up the address associated with that name.
Address
An IP address gives the network a destination for traffic.
Connection
The device uses the answer to begin communicating with the destination.
Mini experiment
Ask the directory
Choose a name. Watch the lookup reveal an address before the connection begins.
Ready. Ask DNS for the selected name.
Knowledge check
Test your address model
Answer five questions. The questions and answer order change each time.