Some thumb rules for basic computer networking operation

• Computer Networks operation principle is similar in many aspects to that of postal networks, in that both use next hop routing and not end-to-end routing. Also there is no concept of end-to-end circuit reservation in both these networks. 
• Each communicating computer need to have at least one IP address to uniquely idenltify it in the network
• Data is split into smaller units called packets and transferred using packet switching. A packet header encapsulation enables each packet to be independently routed through the underlying computer network. 
• At every hop, next hop routing is used to identify a suitable neighbor, that is closer to the destination computer, to pass on the packet in its journey from the source computer to the destination computer.
• Each telecommunication link that is part of the data exchange is not reserved for specific packets and is usually shared between packets belonging to different sessions.
•  Data Link layer and physical layer are together used to carry a packet to the next hop (neighboring computer)?
• Actual data communication between next hop neighboring computers happens at the physical layer through transmission of appropirate electrical/electromagnetic/optical signals
• Computer networks primarily provide two types of services to the application. They are i) a reliable byte stream oriented service and ii) an unreliable best effort message oriented service.
• Layering in computer networks helps in maintaining modularity and simplicity to the whole operation. Hybrid layering model is the one that is practically used.