Question Dummy MACs in Reservation Table

[JDinFlorida]

Wondering if adding multiple dummy MACs into my DHCP reservation table can cause any sort of degradation in speed or security. My router’s reservation table isn't sortable – all reservations are listed in the order that they were added. Just for organizational (OCD) and/or diagnostic purposes, but will adding multiple dummy entries as place-holders for future reservations(s) introduce any connectivity/security/other issues? Any reason(s) for/against? TIA

 

[COLGeek]

No, I wouldn't expect degradation for doing that. I don't see the point, but it should be okay.

 

[Ralston18]

Just read this thread.

Wondering about the point of it as well.

There is the Law of Unintended Consequences....

And Mr. Murphy may make a related cameo appearance.

Without specific reasons and requirements for dummy MAC entries I would forego placeholders.

Just my thoughts on the matter.

 

[Viking2121]

I keep a few in my router to reserve an ip so other devices don't use it so when I got to play around with or test server stuff or nas stuff it wont reserve an ip without a mac, I then set a static ip on the server or device and update the mac for the ip I want it to use in the router, not that it matters really, but I just like a range of ips to use for that kind of thing. OCD I guess.

But no it shouldn't slow anything down or cause a security issue.

 

[Ralston18]

@Viking2121

Are you familar with "arp /a" (Command Prompt) or Powershell's "Get-NetNeighbor" ?

If you have to go in and "update" the placeholder mac then you may as well just forego any such IP "reservations" to begin with.

Instead just use one special or designated Static IP address for testing purposes. (Ensure that that IP address is outside of the DHCP IP address range allowed to the router.)

Create for testing with the applicable mac, delete when done testing. Clean and neat.

Overall, I see no meaningful requirements to reserve IP addresses via bogus/placeholder macs.

OCD or not.

 

[Ralston18]

The original issue/question concerned speed and security - not functionality per se.

You can set up dummy mac's etc as you wish if you wish.

Your system, your environment.

Leaving the dummy mac's in place is just not something I would do as a matter of practice.

 

[NightHawkRMX]

I keep a few in my router to reserve an ip so other devices don't use it so when I got to play around with or test server stuff or nas stuff it wont reserve an ip without a mac, I then set a static ip on the server or device and update the mac for the ip I want it to use in the router, not that it matters really, but I just like a range of ips to use for that kind of thing. OCD I guess.

But no it shouldn't slow anything down or cause a security issue.

For both you and the OP, I'd recommend to use "DHCP excluded addresses" (or similar naming depending on router brand) instead of dummy reservations.

DHCP configuration usually allows you to specify a range of addresses within the DHCP pool that are "excluded" and will not be assigned. It's a common practice in the networking field to leave the first 10 addresses of a DHCP pool/scope excluded in case you need them down the line.

 

[Ralston18]

Good point.

I do sort of the opposite - I just limit the number of allowed DHCP IP addresses and increase the number if and as necessary.

Starting IP address + maximum number of users (192.168.1.101 + 20).

Actually, I should have reduced the max after the last family gathering.

However, with the holidays arriving, I will likely end up just increasing the maximum again.

Leaving at 20.