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How is an IP address associated with a network card?

For example, there are two Windows computers with wireless network cards, and a wireless LAN access point. Both computers are issued DHCP by the access point. How does one computer connect to the other knowing its IP address?
 

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Can you be a bit more specific? Is this a theoretical question, or are you trying to share between machines?
 

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ARP tables held on each computer. ARP stands for address resolution protocol. ARP resolves an IP address to a MAC address. This MAC address is unique and tied exclusively to a NIC. If a host doesn't have an ARP entry for an IP address, it will do an ARP who is broadcast to see if anyone on on that layer 2 segment will answer back with its MAC address.

Hope this makes sense.
 

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In simplest terms, layer 2 is a reference to the OSI model. Layer 1 is your physical connections like your copper cables. Layer 2 refers to LAN traffic. This is where your switched traffic resides in the model. Layer 3 is the next layer up which refers to routed or IP traffic.

If a host receives a response to a ARP resolution broadcast request, it takes the information it receives and puts it into its ARP cache which is also referred to as the ARP table. So now when this host has to send something to an IP address on its layer 2 segment (read same subnet), it will just encapsulate the data in a frame with a destination MAC address it gets from the ARP table. The entries in the ARP table are dynamic and have a set "live" time. If the host doesn't access that entry for a set period of time, the entry ages out and goes away. This helps keep the ARP table relatively clean so the host isn't spending cycles going through a huge ARP table to look of a single entry. You can set a static reservation so an IP address stays persistent with a MAC address but this can and does cause problems. Therefore, it is not recommended.
 
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