data is sent in packets, need an IP address to send it, DNS converts to a human friendly hostname
every packet has headers with sender/receiver addresses
packets first go to NIC (Network Interface Controller on the motherboard), then the router which acts as a gateway and sends the packets forward
routers pass traffic hop-by-hop using routing tables until the packet reaches the recipients local router, uses the IP + MAC to find the exact device
Systems need: physical addresses (MAC), which work as nodes, logical addresses (IP), to route, and routers to connect the different networks and pass traffic through
devices don't need to know the whole path, just the next stop
*in a packet, protocols get added at the beginning or end (encapsulation), headers can be changed for updates
Computers vs. Humans
computers work with numbers, humans with names
converting between the two is essential for human interpretation
OSI Model
7 layers
Physical - sends bits over the actual media (copper wires/ethernet, fiber optic, radio waves)
Data Link - defines how packets get onto the media; handles collisions and confirms the recipient is ready to receive
Network - IP addresses of sender/receiver
Transport - port numbers tell the receiver what the data is for; sender and receiver need to agree on ports