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Le Big Mac

macrumors 68030
Original poster
Jan 7, 2003
2,909
547
Washington, DC
On Airport/TC, what is the difference between these two? In either case, the device will always get the same IP address, right? So is "reserve a DHCP" mean that all the network settings (subnet, dns server, etc.) will get automatically entered?
 
Static ip means it doesn't change and entered manually.

Reserved DHCP means that same ip address is assigned to same device all the time, this is usually done by MAC address of each device.

With reserved DHCP address all info is served by DHCP server. if you have static ip you have to enter it manually
 
Reserved DHCP is useful when you want your router to have full control over how IP addresses are assigned, and for other IP details to be sent to your devices while having manual control of the specific IP address. It's more organised and can make troubleshooting, etc easier. However, although it's very rare some devices don't play nice with reserved DHCP addresses.
 
Thanks, so it's basically what I expected. Seems like reserved DHCP is the best of both worlds, unless the device doesn't play nice for some reason.

Follow-up--in TC menu you can assign DHCP by Mac Address or device name. How can I find out the device name? The TC doesn't seem to show attached devices or allow one to assign a name, even to something like a Macbook.
 
Best to go by MAC address IMO. In a small home network it's unlikely to be a problem (MAC addresses are generally supposed to be unique, but because of the length of the address and how many devices there are out there with a MAC address, it is not unique in practice. But it's very unlikely you'll experience a dupe for home use).
 
MAC addresses are generally supposed to be unique, but because of the length of the address and how many devices there are out there with a MAC address, it is not unique in practice.

I've never heard of this. Care to support that statement?

At 48 bits, there are 281 TRILLION+ possible values - is this just the case of a lazy manufacturer or are you claiming that the world's has 281 trillion devices out there with MAC addresses?
 
I don't know about PC products, but my MBP has a place in the AirPort advanced prefs (I think) that allows you to specify a device name. I prefer the MAC address as well, as that will usually never change unless the hardware is swapped out.

Another advantage that I've found to using reserved DHCP is if you travel with your computer, you don't have to change your IP settings to log on to another network. Before I used reserved DHCP, I was in a coffee shop and although I found the network and it was unsecured, I couldn't log in because my MBP was still trying to use the static IP from my home network.
 
Best to go by MAC address IMO. In a small home network it's unlikely to be a problem (MAC addresses are generally supposed to be unique, but because of the length of the address and how many devices there are out there with a MAC address, it is not unique in practice. But it's very unlikely you'll experience a dupe for home use).

Okay. Only issue I found so far with that is there are separate MAC addresses for the wireless and wired connections, so it looks like I'd need to add both, right?

(Since this isn't an office, if I have the really bad luck to get a duplicate MAC in the 5-10 devices we'll have connected I'll deal with the problem then. But with 281T+, I like my chances).
 
I've never heard of this. Care to support that statement?

At 48 bits, there are 281 TRILLION+ possible values - is this just the case of a lazy manufacturer or are you claiming we have exhausted the possibilities?

My old router gave the option to clone your PC's MAC address... And although it is highly unlikely, unless there was a database with all used MAC addresses to ensure you do not accidentally duplicate one (which there could very well be, in which case my argument doesn't stand), there's no guarantee that the one that's assigned to a device is unique.
 
Another advantage that I've found to using reserved DHCP is if you travel with your computer, you don't have to change your IP settings to log on to another network. Before I used reserved DHCP, I was in a coffee shop and although I found the network and it was unsecured, I couldn't log in because my MBP was still trying to use the static IP from my home network.


Yeah, that's a really good point and reminds me why I liked this option--you can leave the settings at DHCP and not muss with them. particularly good for my wife, who uses a notebook--I don't dare try to teach her how to change the IP settings . . . .:rolleyes:
 
Okay. Only issue I found so far with that is there are separate MAC addresses for the wireless and wired connections, so it looks like I'd need to add both, right?

If you're going to be connecting by both, yes. I think you can reserve the same IP for two different MAC addresses, and since when you're wired you can't be wireless and vice versa, it shouldn't pose a problem.
 
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