Just started a new job out of college and the network was down when I got there, coul dreally use a hand

I just started a new job out of college as IT, and today was my first day. The internet went down last friday and I cant figure out how to get it back up.

We have a Cisco router that outputs to a D-link switch. This switch is connected to our domain controller an application server and a couple of server room computers, These computers have internet access.
The D-link switch has 16 ports about 12 are being used 1 - application server, 2 - DC, 3 - My IT computer, 4 - Goes to the switch room in the basement, the rest are used for VOIP and security

The Cable that goes to the switch room connects to an HP 1800-24 which splits into 2 other HP 1800-24s and a couple patch panels.

I cant seem to get the internet to propagate these switches. I’ve talked to the previous IT guy and He suggested I reboot the Cisco router and the HP switches and just let the routing tables do their thing but that didn’t work.
I’m currently trying to map out the network and figure it out but I don’t really know what to do.

Any suggestions?
All computers have network connection to connect to the Domain Controller but the Network storage isn’t accessible.
I can only connect to 1 switches web portal when I wire my laptop to it, the other 2 don’t give my anything.

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did you review the documentation?

what have you ruled out?

I’m reading the documentation right now but I haven’t been able to get far, I spent my day just figuring out what they had and where it was.

So the ISP modem connects to the cisco router which connects to an unmanaged switch. some of the computers attached to that switch have internet, but when I connected my laptop no luck. The Cable that connects the unmanaged d-link switch to the HP managed switch in the basement has internet when I connect it to my computer.

I haven’t checked whether it still has internet when it gets to the basement because that cable gets lost in the weeds.

After rebooting the managed switches in the basement 2 of them don’t allow me to connect to the web ui and show power indicator but no network indications while the third switch shows partial life with about half of the plugged-in ports showing network indicator lights. So I think it has to do with these switches hp 1800-24g but I can’t figure out why 2 of the 3 don’t grab an IP address from the DHCP on reboot.

Maybe it’s an issue with the DHCP server, I haven’t been looking for it so I don’t know where or what device it is.

I’m not sure where to start with ruling things out, I know that their is internet at the modem, the router attached to the modem and the unmanaged switch connected to the router. After that It goes into a wall jack and gets lost in the switch closets wire mess.

probably some addresses got reallocated in dhcp (which likely cause issues with the “routing tables doin their thing”),

might have to find the gateway ip and go from there.

also check the subn masks

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A rogue DHCP server could also cause problems.
Check the servers and the router for a DHCP server.
The Cisco router might not have had it’s config not saved to nvram and lost the running config in a power cut.
If you’re replacing previous staff then they might have left a trap.


Congrats on starting a new job.

The overall strategy you’ve chosen - traverse everything top down sounds sgtm.

Was about to mention, as @NZSNIPER and @DrunkByDefault may be alluding to… Move your switches onto static IPs - since you only have a handful.

Re wire mess:

There exist these mustard yellow cheap $20 RJ45 toner (cable finder) devices you can get that will help you with unlabeled cables and ports that you don’t know where they’re going. Get a labeler and make sure you label each side of each wire.

Build a topology map from there either on pen and paper or on s tablet in some small note taking tool.

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Another useful tool is nmap. Let it scan the network and the ui will display a topology. (you need the separate ui package alongside the normal tool)

Like others said, you may have become the innocent victim of a previous tech’s vendetta against his former employer. You may want to start afresh, with known values (i.e. new switches) to set up a new network topology that’s properly labelled/documented.


Thank you all for your help, I just purchased and installed 2 new switches to replace ProCurve 1 and ProCurve 3 and my networking issues were resolved. It was my first instinct but I was skeptical that 2 switches would just die on the same day, but replacing them got the network up and running fine, I’m going to spend the next little while mapping my network and resolving why I cant connect to my Domain Controller to sign in with my new Admin account, but thank you all for your help.


Perform a factory reset on the switches you’ve replaced to see if they come back to life again. If they do, keep them as spares. If not, flog’m off at 50 bucks a piece for spare parts or something.

You may need to start a recovery procedure for the DC.

No I’ve already started the RMA process so that I can have them as working spares in the case that this ever happens again