DHCP Logic
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@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.
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@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.
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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.
Why would you need a new mac address? You can easily change mac addresses on VM's all day long.
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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.
Versus what? Redoing the static IP settings anyways? I'll rather re-enter a MAC than dick around in Windows network settings.
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@obsolesce said in DHCP Logic:
@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.
Versus what? Redoing the static IP settings anyways? I'll rather re-enter a MAC than dick around in Windows network settings.
Yeah, this would make sense if you had only a handful of clients that needed to be statically assigned. Nothing needs to be statically assigned. So long as your DHCP server is functional.
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And this loops back to, if you lose your DHCP server (and nothing is statically assigned) why not have a redundant DHCP server?
Or restore from backup.
Lots of reasons to really question the whole argument.
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It comes down to there being so many benefits to using DHCP reservations in most cases, versus a bunch of made up scenarios not to, that do not matter at all. This feels like the virtualize vs not virtualize servers discussion.
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@obsolesce said in DHCP Logic:
This feels like the virtualize vs not virtualize servers discussion.
^ this.
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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.
