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Once connected, but now no IP

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by mr_t_wright 1 view

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Hello all I am having a issue, so I put a 8 port switch in the wall jack which is connected to a 24pt Cisco switch, on the initial install of the switch I connected 4 pcs all of which could access the internet and would pull and IP, However now about two weeks later I was called about these four pc's none would connect to the internet, I noticed that IT guy that was there changed the DNS from automatic to a static, now I put it back to auto and the first two pc's grabbed an IP however the third and fourth will not. Only two pc will get an ip now where before all 4 got an IP with no problem. I changed the 8pt switch same problem so its not that switch, can anyone help me isolate this issue?

7 replies

by cmiller5400

Are the ports auto MDI/MDIX on the switch(s) if you do not have a crossover cable on them? Are the speed/duplex set alike on the switchports they are plugged into (ie. auto/auto, 100/full for the connection)

Is there a rogue DHCP server somewhere on the network?

On the DHCP server, are their enough addresses in the lease space/range?

DNS and DHCP are two different beasts... Did you state the wrong one in your post?

by mr_t_wright

Yes, they are and the DHCP is coming from ther server. I don't know what you mean by "boucned..."

by tobif

The thumb rule is to keep one question in one thread:

If you have a problem and want some help, start your own question-thread, even if your problem very much reminds of a problem someone else had 3 years ago. (If you revive an old thread with additional questions or remotely related information, risk is that someone will name this a "Zombie", a dead thread that starts "walking".)

In the same way, you'll upset people if you spawn several threads about the same question. This may make people spending time on answering a question that already was solved in the other thread. So, if you start more than one thread, try to direct everyone to one of them.

If your question has "dropped out of visibility" but you still need an answer, you may return it to the list of latest questions by adding a new comment, a "bump". But at the same time, think a moment, did you give enough input for other people to actually help you? Better than just a "People, I'm still looking" can be to add something you forgot to include the first time around.

Edit: I first wrote bounce, should be bump

by enforcer drive

After changing adapters back to automatic are you running ipconfig /release and ipconfig /renew?

by robo_dev

The Cisco switch will be seeing a whole lotta mac addresses on that one port. If port security is enabled, it would stop some devices from connecting.

I would look at the logs of the Cisco switch and see if perhaps it is mis-negotiating the duplex settings of the port. An ethernet connection will work, sort of, if the switch is going full duplex and the device is going half duplex.

If the CRC errors are in the millions for that port, then the two devices are not playing well together.

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