TCP/IP & Networking: The Network is NEVER Reliable
Visualization: 1. The Network Stack & IP Addressing
Layer 7: App
HTTP / Payload
Layer 4: TCP
Ports
Layer 3: IP
IP Addresses
Layer 2: Eth
MAC Addresses
Layer 1: Physical
Fiber / Copper
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DOWNLOADING CONCEPT: 1. THE NETWORK STACK & IP ADDRESSING...
↳The network stack is a series of encapsulation layers (the OSI Model).
↳When your application sends an HTTP response, it sits at Layer 7 (Application).
↳The OS kernel wraps this data in a Layer 4 (Transport) TCP segment (adding source/dest ports).
↳Then it wraps it in a Layer 3 (Network) IP packet (adding source/dest IP addresses).
↳Finally, it wraps it in a Layer 2 (Data Link) Ethernet frame (adding MAC addresses).
IP Addressing
↳(Layer 3) is how machines find each other.
↳IPv4 addresses are 32-bit (e.g., 192.168.1.5).
↳Because we ran out of IPv4 addresses, we rely heavily on NAT (Network Address Translation), which translates a single public IP to multiple private IPs.
Command
ip addr Shows your network interfaces and their assigned IP addresses.
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9001 qdisc mq state UP
link/ether 06:b0:b1:a4:23:11 brd ff:ff:ff:ff:ff:ff
inet 10.0.4.17/24 brd 10.0.4.255 scope global eth0
▲ LIVE INCIDENTApp logs show: Cannot assign requested address.