I am new to networking as such, but I have been searching a lot about the problem of finding IP from MAC for the past couple of days. I have a device whose MAC address I know and I have an Android app running in my smart phone. I need to find the IP of the said device so that I can send requests to it.

On the same subnet the ways I found were to either use an external cloud server or to ping all devices in the subnet and read the ARP table. I don't want to use an external server so I went with ARP and its working fine...

However, for the case of a different subnet I am not sure how to accomplish this. Is this possible? If it is not, addition of what extra knowledge could make it possible?

Let's say I have the IP of the router that the device is connected to or the Gateway IP which the device connects to..can I use any of those to reach the device's subnet somehow? ( I really am pretty new so bear with me if I am saying something stupid)

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    It's not possible. MAC addresses do not cross Routers/Switches etc. – DavidPostill Jan 6 '16 at 14:20
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    You can ping any device anywhere (as long as it is connected and pings are not blocked). However you cannot get a MAC Address using ping. – DavidPostill Jan 6 '16 at 14:43
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    Ping to a different private subnet is only possible if they share the same gateway and have appropriate subnet masks. – DavidPostill Jan 6 '16 at 14:50
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    There is no universal solution to this issue, so usually the only remaining workaround is to look for services on the box that may leak the MAC, like Samba/CIFS, SNMP, or WMI. each of them can be interrogated to retrieve the MAC. – Frank Thomas Jan 6 '16 at 15:54
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    @DavidPostill, "Switch fabric" is a topology-agnostic term for a set of interconnected layer2 intermediary systems (switches, bridges, or even repeaters), with a connotation of focus on hardware and cable plant. usually they are depicted graphically as a Mesh since its kind of a maximally complicated example, but a single isolated switch is a fabric unto itself (in fact the original definition came from crossbar switch design, for backplanes). Since they are layer2 devices, its comparable to a Broadcast domain, absent VLan or P2P-link scenarios. en.wikipedia.org/wiki/Switched_fabric – Frank Thomas Jan 7 '16 at 0:16

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