Domain names, DNS and IP addressing – subnet masks and routing

Computer ScienceNetworks & the InternetAges 15–16

Type a domain name and a DNS server looks it up in a table to return the matching IP address. The program then ANDs your device's IP address with the subnet mask to get the network address, does the same for the destination, and compares them: the same network address means the two devices talk directly, a different one means the packet must travel through a router over several hops. You can view the whole AND operation in binary and watch the packet move on the diagram.