What happens when there is a duplicate MAC address?

A duplicated MAC address means you have multiple devices responding to data requests as if they are the only device with that address on the network, or you have a switch that keeps changing the port assignment for that address because the switch keeps seeing the device’s MAC address moving from port to port.

Can a two devices have same MAC address?

No two devices on a local network should ever have the same MAC address. If that does happen, both devices will have communications problems because the local network will get confused about which device should receive the packet.

Can MAC address be detected?

Technically, a MAC address can be only traced on the network that it is currently connected to. In other words, your computer at home can see the MAC addresses of other computers that are at your house because they are on the same network.

How is a unique MAC address assigned to a network card?

A MAC address is given to a network adapter when it is manufactured. It is hardwired or hard-coded onto your computer’s network interface card (NIC) and is unique to it. Something called the ARP (Address Resolution Protocol) translates an IP address into a MAC address.

Why does my router have 2 MAC addresses?

Each network interface has its own unique MAC address, assigned by the vendor of the equipment. So if you have a wired and a wireless interface you will see two addresses.

Can MAC address be duplicated?

Remember, duplicate MACs are “allowed”, as far as any out-of-the-box Ethernet switch is concerned– they just cause a problem that will interrupt network connectivity to each host in question.

Can two network interfaces have the same IP address?

You cannot use the same IP address on multiple interfaces. It just won’t work properly (usually it will only work on the last interface the IP was assigned on). You need to put the ethernet interfaces into a bridge and assign the IP address on the bridge itself.

How are MAC addresses used in networks?

A MAC address is a unique serial number assigned to each network interface controller (NIC) . This allows a network to uniquely identify any device, even when a dynamic IP address is assigned using DHCP, each time the device connects to a network.

Why would a device have two MAC addresses?

For each network interface in your device, there is a unique MAC address associated with it. So if your laptop has both an Ethernet port and Wi-Fi built-in, you will see two MAC addresses in the system configuration.

How to detect duplicate MAC addresses on a switch?

I think most of the bigger switch vendors have management tools that can help you detect duplicate MAC addresses. 3Com has something called Transcend Status Watch. If you have Dell switches, look into OpenManage Network Manager. Was this post helpful?

How do I remove a duplicate IP address from a switch?

Shut that interface, “clear arp” ping the “duplicate IP” from the switch, do a “show arp | inc ” again, it should be listed now with a different MAC. That’s pretty good.

What happens if two machines have the same MAC address?

It will have learned the MAC addresses of these two endpoints. If by some chance both of these machines claim to have duplicate MAC addresses, the switch will not know what to do with that traffic. In fact, if I added a router to this picture.

Is there such a thing as a duplicated Mac?

I agree that duplicated MAC is rare in most Corporate network. However; in development environment, especially QA Lab they often foget to change the MAC on phototype , and then it will create a mess traffic on your LAN and frozen your switch..etc.