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web solution + GSM/GPRS modem: best way to communicate
Networking: How Does A Packet Know Where To Go?
BorysSokolov posted a topic in MiscellaneousI'm trying to learn more about the hardware aspect of web development, and networking - particularly TCP/IP, and I figured there must be an expert on internet infrastructure somewhere on these forums I've read up a little on the subject, but so far all I've got is a bundle of random information that don't seem to "click" together, so I'm looking for someone to fill in the gaps. The main question I have is, how exactly does a computer know where to send an internet request?; since that's a pretty broad question I'll just list what I know so far, and if you find an an error, or if I'm missing something, please let me know. Alright, so suppose I am on my local PC, and I'm trying to access a website. I type in www.randomsite.com, and the computer contacts the DNS server to fetch the domain's IP address. Let's say it's 184.108.40.206. At this point, the computer knows the public IP of the destination, but still hasn't figured out where exactly the address lies. So, it sends the information somewhere (or is this still done within the computer?), where it is determined whether the destination IP is on the local network, or outside the network. If the address is calculated to exist within the LAN, then the packet is labeled with the MAC address of the destination and sent to the correct host; however, if the destination exists outside the local network, the packet is handed over to the default gateway, that then routes it through, onto the internet, where it is then the ISPs job to get it to its correct address. Once the packet reaches the destination network, a port (in this case most likely port 80) forwards it to the host, which packs it with the requested information (does it make a new packet or just reuse the old one?), and sends it back to the source network. Then, my router receives the packet, and somehow remembering which device requested it, sends it back to my computer, displaying the website on my screen (obviously, more than once packet would need to be sent). Phew...is this at least the basic concept? Or am I missing something? Thanks in advance.