System Architecture Visualization
1. Browser
Requests google.com
2. DNS Resolver
Returns 142.250.72.14
3. Local Router
Provides MAC via ARP
4. Google Server
Port 443
Press enter or space to select a node. You can then use the arrow keys to move the node around. Press delete to remove it and escape to cancel.
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DOWNLOADING CONCEPT: PHASE 1: ADDRESS RESOLUTION (DNS & ARP)...
The DNS Lookup
- ↳Your computer cannot route packets to 'google.com'.
- ↳It needs an IP address.
- ↳The browser checks its local cache.
- ↳If missing, it asks the OS.
- ↳If missing, it queries your ISP's DNS resolver.
- ↳The resolver traverses the DNS hierarchy (Root → TLD → Authoritative) and returns the IP (e.g.,
142.250.72.14).
The ARP Broadcast
- ↳Now your computer has the destination IP, but how does the packet physically leave your laptop? Your computer must send the packet to your local router (Default Gateway).
- ↳But Wi-Fi and Ethernet chips don't understand IP addresses; they only understand MAC addresses (hardware IDs).
- ↳Your computer shouts an ARP (Address Resolution Protocol) broadcast to the local network: 'Who has the IP of the router? Tell me your MAC address!'.
- ↳The router replies with its MAC address.
- ↳Finally, the packet is framed and transmitted over the airwaves to the router.
▲ LIVE INCIDENTUsers report 'This site can't be reached' errors.
sre@arena:~/internet-basics
sre@arena:~$ dig google.com +short