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In a network many servers and workstations and cameras DVR are working together but any instant the MAC address of one server (ip-192.168.12.1) and DVR (ip 192.168.12.176) which have different MAC address, was automatically changed and make same.The ping status of that server and DVR is break. connectivity is down what I do?

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closed as unclear what you're asking by Chopper3, kce, Ward, Scott Pack, mdpc Jul 31 '13 at 6:23

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I'm not sure I follow you, but if you're saying that a server and a DVR have the same MAC address on the same LAN, and this is breaking connectivity, that makes perfect sense. To fix it, they must have different MAC addresses. –  MadHatter Jul 30 '13 at 10:35

2 Answers 2

The 48 bits of Media Access control (MAC) are supposed to be unique. Always.

This means that two NICs on the same network can always be distinguished by their unique MACs.

If you purposefully break this by giving multiple NICs the same MAC then things will break.

Solution: Never use the same MAC. (And usually,Never bother changing it. A MAC is like an unique serial number. The manufacturers make sure that you get this unique number per device. There is no good reason why you should ever need to change that.)

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Go change the MAC address back to what it was before.

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