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I have couple of questions/doubts which I would like to get some advise on.

Question#1 Suppose a STA A in infrastructure mode wants to send data to an exterior host (STA B), residing in different network. In such case, what will be the destination data link address of the Wi-Fi frame sent from STA A? Is it the MAC address of the Wi-Fi AP (which contains the router inbuilt in it)?

Quesiotn#2 Another question is, when a WAP receives a Wi-Fi frame from a STA connected to it, and finds that the destination MAC or DA in the frame is different from its own, then, does it simply forward the frame to the next WAP or next STA (whichever matches MAC address to the destination field) without sending the frame for Layer3 processing? Or in other words, does the WAP send the frame to the layer 3 processing ONLY if the destination MAC or DA in the frame matches with its own MAC?

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Q1: ... wants to send data to an exterior host (STA B), residing in different network

That's not possible via data link layer alone. The host needs to use a network-layer protocol like IP and direct the encapsulating frame to a router/gateway in between the networks (which has nothing to do with Wi-Fi). For (off-topic) consumer-grade devices that may be the same box as the WAP, but that isn't usually the case in on-topic business networks.

Q2: From the networking perspective, a WAP is a bridge: it forwards frames based on their destination MAC addresses.

Only when the destination MAC address is that of the WAP and the WAP has got some network-layer functionality itself (routing, console, web interface, ...) then it processes the payload of the frame on the network layer (IP and potentially further up):

If the destination IP address belongs to the WAP the packet is directly addressed to the WAP and it's processed locally. With any other destination IP address, the packet is processed by the routing function (when present) and forwarded accordingly.

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  • Thanks for the answers. Ans#2 is fully clear. For question#1, I can understand this part, that its not only L2 layer functionality to send data to host in different network. My query is more related to the L2 layer frame (Wi-Fi). I just wanted to understand, does the WiFi frame in such case, would contain MAC of the AP as destination address or something else? I read that DA or destination address should be present in the Wi-Fi frame as one of the addresses. So, my question was from that perspective only Oct 8 '21 at 13:44
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    I've expanded the answer a bit, hope it becomes clearer now.
    – Zac67
    Oct 8 '21 at 13:58
  • Fully clear now! Really appreciate. Thanks. This pops up a new question to my head. How does the hosts (STA A) connected to the WAP (with routing functionality) come to learn about the MAC of the WAP? Oct 8 '21 at 14:14
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    A wireless client learns the WAP MAC address by SSID broadcast and as part of its login procedure. Don't forget to vote for useful answers and eventually accept a satisfying answer.
    – Zac67
    Oct 8 '21 at 14:28
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    This should help: networkengineering.stackexchange.com/help/someone-answers
    – Zac67
    Oct 8 '21 at 14:41

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