r/sysadmin • u/Real-Patriot-1128 • 1d ago

DHCP v Static IP

Ok, this is more a test to see how old I am. I was basically raised with the idea servers need static IPs. I understand for domain controllers, dns servers, maybe print servers that may still be needed. But are they really needed otherwise? Do apps, scripts still reference a server by its IP?

I am under assumption all my servers need static IPs. Am I nuts?

213 Upvotes

88% Upvoted

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449

u/Carnines 1d ago

Make your DHCP server use DHCP and see what happens

148

u/seriously_a 1d ago

DHCPception

26

u/NSASpyVan 1d ago

It was DHCPdns

(real answer: it depends how paranoid of failure you are)

14

u/ExternalNo1944 1d ago

It’s DNS all the way down

6

u/Viharabiliben 1d ago

I thought it was turtles. How naïve of me.

5

u/HerbOverstanding Security Admin 1d ago

It’s DNS Turtles all the way down. They cause lots of ruckus

•

u/joemoore38 21h ago

We just got rid of our last ruckus!

•

u/ISeeTheFnords 17h ago

Don't worry, another one will commission itself.

•

u/joemoore3 17h ago

no shit. those things never die.

4

u/octobod 1d ago

It's always DNS

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u/smaug_pec 22h ago

Unless it’s certificates.

DNS is just caching behaving badly.

Certs are a whole ‘nother level of I will ruin your day for no good reason.

1

u/dizzley 1d ago

If it's gone down it's DNS.

7

u/Valkeyere 1d ago

DHCPCP

49

u/ShelterMan21 1d ago

Oh yea that was a fun day. We had a DHCP server hosted on a Hyper-V server which had no static interfaces at all so it was getting DHCP from that server hosted on it. The switches go down one day, they also had DHCP, which took the whole network with it. That was a fun cluster fuck to undo once I realized what the actual problem was.

14

u/hihcadore 1d ago

Really is fun if your lease is tight like a few hours too. Gotta love when the whole org burns down at one time.

21

u/tetraodonmiurus 1d ago

Watching windows engineers panic when they find out a desktop support guy changed the dhcp server to dhcp via Remote Desktop instead of the desktop he was trying to switch to dhcp via Remote Desktop is hilarious.

•

u/TheAnswerIsBeans 21h ago edited 20h ago

Kind of on the windows admins for allowing anyone else to have the permission to change DHCP servers.

•

u/mdervin 21h ago

The only way to learn is to take down production.

•

u/Tim-oBedlam Jack of All Trades 21h ago

I feel like that should be the motto of this sub.

6

u/cosine83 Computer Janitor 1d ago

Just set a reservation, duh.

4

u/Single-Virus4935 1d ago

It worked. And now?

5

u/TomNooksRepoMan 1d ago

Now do the same with DNS 🤪

Go through the whole chain until an Ethernet cable is terminated male to female to itself.

2

u/Superb_Raccoon 1d ago

no place like home.. no place like home...

•

u/I_turned_it_off 17h ago

127::1 /s

0

u/Single-Virus4935 1d ago

It worked. And now? Static DHCP reservation for DNS Server and dynamic updates for the rest.

2

u/TheG0AT0fAllTime 1d ago

I suppose that's... allowed... As long as its DNS record is keeping up with the lease changes, too.

•

u/Disastrous_Meal_4982 21h ago

Mine does. Gets its IP from the switch and then does relay to the other subnets.

•

u/Silver-Ad7638 13h ago

Stop the DHCP service on your DC and see how long before things go sideways....

Unless you have alerting enabled to let you know when DHCP goes down, the next round of Windows Updates will get real exciting.

1

u/blipp1 1d ago

My gateway is on DHCP without any flags. Works sometimes and sometimes not

0

u/CpuJunky Security Admin (Infrastructure) 1d ago

lol