When sending packets in a network, do the PC's all have to share the same subnet mask or can you dedicate comps to mask addresses? I am wondering if this also determines collisions and if it is a requirement for a three-way handshake.
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1Subnet masks aren't related to collisions or handshakes. To simplify a bit, collisions are a layer 1 (physical) thing, subnet masks are layer 3 (and its relation to layer 2), and the 3-way handshake is layer 5 (TCP session). – Gordon Davisson Oct 06 '22 at 19:41
1 Answers
For a host to send packets to other hosts, they do not need to be on the same network, but having different source and destination networks requires a router to route packets between networks. A network mask determines which part of an address is the network, and which part is the host.
A host will mask the destination address with its configured mask to determine if the destination is on the same network. If not, it sends the frame containing the packet to its configured gateway, not the destination host. If the destination is on the same network, then the host sends the frame containing the packet directly to the destination host.
If you misconfigure the network mask on the hosts that are on the same layer-2 broadcast domain, some hosts may see a local destination host as a a destination on a different network and send the packet to its configured gateway, so the packet never reaches the destination.
You can read all about masks and subnetting in this two-part answer.

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