DHCP Logic
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@dustinb3403 said in DHCP Logic:
@pete-s said in DHCP Logic:
If the DHCP server doesn't come up after power failure, the rest of the servers booting up will not use their last given ip address if that is what you think. They will not have an IP address at all.
Is that really a concern though. If your entire business infrastructure is offline due to a power outage, aren't there bigger items to address?
Like why in the hell did we lose power?!
Reservations would provide the same IP's to their respective clients once the DHCP server came up. Statically assigned on top of that would mean you don't even need the DHCP server. So long as the network itself is functional.
Exactly, when DHCP doesn't work, nothing matters anyway.
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@pete-s said in DHCP Logic:
@donahue said in DHCP Logic:
I like the idea of reservations because in theory everything could be managed and organized from the DHCP server. That being said, I have not really used reservations for this purpose yet, too many other things on my plate.
That is another problem. It means that if you are replacing server hardware or a NIC you also have to have access and redo the dhcp reservation since you have new mac addresses.
That's the most trivial thing ever. Takes two seconds. The nice thing is that you have the DHCP system as true, up to date documentation at all times, and can use that as a source of truth for DNS. With straight static IPs, it's all manual, each step of it. So many things to go wrong when DHCP Reservations automatically fix that stuff.
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To help separate this.
DHCP servers aren't critical for a network to operate. They are nice to haves, because anything that connects to your network is immediately given an IP address.
You can skip that automatic process entirely, and statically assign every device. Nothing in the below screenshot says "DHCP Server" as some key factor to using the network or internet.
DHCP Servers simply make life easier, while creating questions like with the OP.
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Having just done an IP scheme change a month or so ago, I'm A DHCP Reservations believer. Made the process so simple.
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@zachary715 said in DHCP Logic:
Having just done an IP scheme change a month or so ago, I'm A DHCP Reservations believer. Made the process so simple.
Out of curiosity, was a Windows Server handling DHCP for the network?
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@travisdh1 said in DHCP Logic:
@zachary715 said in DHCP Logic:
Having just done an IP scheme change a month or so ago, I'm A DHCP Reservations believer. Made the process so simple.
Out of curiosity, was a Windows Server handling DHCP for the network?
Why would this matter? I've done the same thing with Windows DHCP and with router DHCP. Both are fairly trivial.Just watch the details. Like anything.
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@scottalanmiller said in DHCP Logic:
@g-i-jones said in DHCP Logic:
@scottalanmiller Nah, you can set them outside the scope or in the scope. I prefer to put them outside the scope because i like to think i have my own little secret cubbyhole for IP's that no one can take, and I strive for super organization.
Being in or out of scope has no bearing on that.
What are you referring to?
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@g-i-jones Why do you keep deleting your posts. . .
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Is Windows the only DHCP server that allows static mapping within a scope?
pfSense only allows you to static map outside the scope/pool. -
@g-i-jones said in DHCP Logic:
@scottalanmiller said in DHCP Logic:
@g-i-jones said in DHCP Logic:
@scottalanmiller Nah, you can set them outside the scope or in the scope. I prefer to put them outside the scope because i like to think i have my own little secret cubbyhole for IP's that no one can take, and I strive for super organization.
Being in or out of scope has no bearing on that.
What are you referring to?
A DHCP scope is a valid range of IP addresses that are available for assignment or lease to client computers on a particular subnet.
This means if you are assigning an IP address, it's a part of the "available to assign" IPs no matter if there is a reservation or not a part of the DHCP range that isn't a part of the pool, that is using for example 192.168.1.1-50 and than 51-255 would be the usable IPs range. Would add whatever reservations you create within the 1-50 pool to the scope.
As they need to be managed by the DHCP server.
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@dustinb3403 lol, trying to figure things out, man.
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@dustinb3403 yea, that's exactly what I was saying, but I'm confused about what scott said. I don't get why he said that. Like no bearing on what?
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The critical thing to know here is "available for assignment".
Creating a reservation immediately makes that address "available for assignment" regardless of if its in the pool or not in any GUI you're looking at.
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@dustinb3403 yea, I'm not confused about anything DHCP, just what scott said and what he meant.
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@pete-s said in DHCP Logic:
It's another question but it's debatable if DHCP reservations is a good idea in the first place. In general I would say no.
Better to use static IPs, at least for anything that is important.I disagree entirely. Here's why. You rely on a static IP for a printer right? Because you don't want them switching up all the time, but printers do go to standby mode, and then now you have a samsung phone (seems to always be the damn samsungs) that steals that IP and now the printer doesn't work. Happens all the time. I typically do both; I'll set a static IP for a printer, and then make the reservation on the DHCP server. This way nothing steals it. Additionally I'll do this same thing with anything of importance that has a static IP.
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@g-i-jones For static IP's in a pool we will do an Exclude on that IP. That stops things from taking the IP as it removes it.,
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@g-i-jones said in DHCP Logic:
@pete-s said in DHCP Logic:
It's another question but it's debatable if DHCP reservations is a good idea in the first place. In general I would say no.
Better to use static IPs, at least for anything that is important.I disagree entirely. Here's why. You rely on a static IP for a printer right? Because you don't want them switching up all the time, but printers do go to standby mode, and then now you have a samsung phone (seems to always be the damn samsungs) that steals that IP and now the printer doesn't work. Happens all the time. I typically do both; I'll set a static IP for a printer, and then make the reservation on the DHCP server. This way nothing steals it. Additionally I'll do this same thing with anything of importance that has a static IP.
But why not just statically assign an IP that isn't in the available pool? That IP would never be available to be handed out, and still statically assigned permanently.
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@hobbit666 I see. Is there any benefits to doing exclude ip over just setting reservations in your opinion?
