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I'm connecting a few Raspberry Pi Zeros together over Ethernet through a switch on a subnet. I've assigned them all static IP addresses and I'm wondering if that is adequate or if I also need to assign them each a MAC address (since Raspberry Pi Zeros don't come with a MAC address).

Do I need to give them all MAC addresses/will having MAC addresses speed up data transmission between them. Or is it fine to just stick with static IP addresses?

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    As the answers noted, if you have an Ethernet port (whether built-in, added on or via USB adapter), you have a factory-assigned MAC address. The only place I have found where you can relatively easily change a MAC address is some routers will let you override the default MAC address for purposes of spoofing a previous router or other device to fool a cable modem, which shouldn't be necessary at all - yet sometimes is. – manassehkatz Sep 7 '18 at 20:33
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    @manadsehkatz There’s a lot of software out there that lets you arbitrarily change or spoof a MAC address, too. It’s not at all a hard problem. – HopelessN00b Sep 7 '18 at 21:53
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    @HopelessN00b I knew people would latch onto “But you know you can spoof a MAC address, right?” and such. But for pretty much 99.9% of the usage cases out there utterly nobody knows, cares or “spoofs” MAC addresses. – JakeGould Sep 7 '18 at 23:08
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If you are networking in any way with common networking interfaces you have MAC addresses whether you know it or not but you shouldn’t really have to worry about them.

So, I understand your question but it’s still a bit confusing when you ask something like this:

…I'm wondering if that is adequate or if I also need to assign them each a MAC address (since Raspberry Pi Zeros don't come with a MAC address).

So this is what a Raspberry Pi Zero looks like:

Raspberry Pi Zero

It obviously does not have any networking ports built in; I assume you mean Ethernet since you mention a Switch. So I assume you are using some kind of USB to Ethernet adapter?

While you are correct that the Raspberry Pi Zero does not have a built-in networking port—and thus does not have a MAC address—a networking device like a USB to Ethernet adapter definitely does have a MAC address.

That said, you ask:

Do I need to give them all MAC addresses/will having MAC addresses speed up data transmission between them. Or is it fine to just stick with static IP addresses?

You are mixing things up. For the most part, any common basic networking device of any kind—wired, wireless, etc…—will have a MAC address which is a media access control address. An IP address is the network address. You connect devices together via IP addresses, but MAC addresses are pretty much invisible to you as an end user and are only really used by networking equipment—like switches—to help manage traffic.

So you don’t need to ever think about assigning a MAC address in the same way you assign an IP address. A MAC address is unique to a networking interface and is hard-coded in at the factory. An IP address is what you are managing when you—a user—sets up a system and related devices. And speed is not determined by MAC addresses; it’s simply a lower-level control item you really don’t need to think about.

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A MAC address is a hardware identification number that uniquely identifies each device on a network. The MAC address is manufactured into every network card.

Your Raspberry Pi has a MAC address built in from the factory if it has any kind of network card. You can't have a working IP address solution without having a MAC address layer under it. The MAC address is at layer 2 of the OSI model. TCP is at level four, TCP/IP depends and requires MAC to work.

Here is a way to find your MAC address on a Raspberry Pi:

https://raspberrypi.stackexchange.com/questions/71824/how-can-i-find-the-mac-address-of-my-wi-fi-interface

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    While IP depends on a MAC layer, not all MAC layers have a MAC address. In particular point-to-point links don't need one (because there's only one place that MAC frames can go to anyway), and some types don't have one. – grawity Sep 8 '18 at 10:09

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