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my network is going crazy!!! PLEASE HELP!!

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by marco136669

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Our schools network is going crazy, first i thought it was a problem with the switch(24 Port DLink) but we changed the switch and only plugged in the cable that goes to the server and a computer but it doesn't seem to locate any computers on the network, but sometimes it works fine without giving any trouble. we have 5 Switches which connects each other and all the computers in the network and all are handled by a server, the funny thing is all the PC's upstairs(which uses another switch) are working fine most of the time but the PC's in the ground floor doesn't seem to have any connectivity most of the time, last night it worked and today morning it didn't and again now its working but it doesn't allow any access to any folders on the server. so i'm really clueless of what is happening right now. so please advice on what i can do, it is definitely not a virus on the server as i have scanned it with Kespersky.

16 replies

by seanferd

"we changed the switch and only plugged in the cable that goes to the server and a computer but it doesn't seem to locate any computers on the network"

Try replacing the cable?
Is the cable too long?
Is the cable unshielded or subject to heavy interference from radio or electrical cables?
Is it a smart switch that is supposed to configure itself?
Has the server been misconfigured in DHCP or DNS?

"doesn't allow any access to any folders on the server."

This may be an entirely separate problem. Cover the first problem, and we can move on if the folders don't become accessible.

by marco136669

the cable is very long but i don't see any physical damage to it and the entire week it was working fine and only on Friday(Is the weekend in Maldives) morning all this happened.

Yes it is a smart switch which configures itself.

I have restarted the services from the server thinking that it is something to do with the configuration, and the really funny thing is for an year this network was working without any trouble until last Friday.

by seanferd

Sometimes due to sagging/stretching until they are no longer properly terminated, or until either the termination or socket is deformed just enough to fail.

Is there a cleaning/housekeeping staff that that takes care of this room?

Anyone recently run an electrical cable near or across the network cable?

Could the switch have auto-configured differently than the previous switch was configured (if the old switch did go bad)?

The only other things I can think of are software on the segment that is problematic.

If something new was installed which either has some security feature, or had tripped a feature in existing security software (Symantec Endpoint Protection has caused some folks endless bafflement by suddenly blocking file or network access due to a software update somewhere else).

Or, if routing or DNS configuration was somehow changed.

I can only approach this in generalities for the most part. Perhaps someone more expert in networks your size will find your question here.

P.S.

You may get more of a response if you did re-post this as a Question, as you have this on the Discussion side of the forum.
https://www.techrepublic.com.com/5200-6230-0.html?contentType=2

You can link back to your original post here to let folks see what you have already discussed.

by dayen

We had somthing like that our Domain user on the clients computers vanish until we booted in safe mode left it there 3 min and then re booted and they came back. when they were gone whe tried to put them back and it said no trustrelationship between client and server don't even know it this is close but it was last week after security update from microsoft. we could no longer see our folders at that point.

by marco136669

i checked the entire school for a physical damage to any network cable but i dont seem to find any and i check if a cable coming out from the switch is coming back to the switch without passing thru a computer and didnt even seem to find that problem, so i suspected someone trying to hack into the system(a person who knows the passwords and everything) so therefore i changed the server password and for now everything seems going good. so hoping it will be fine thru out the year. if any problem rises will let you guys know. thank you all very much

by cg it

network guy using Please Help me in the subject... whenever I see that, I ignor it. Only high school kids use that Please Help Me dog and pony show.

Another case of someone that doesn't have anything else better to do than think up questions for TR forums and use Please Help Me.

by dayen

Ha I use the words please and thank you. is that because I over 60. has our world become jaded to such a point that please is a joke with kids, just sad

by jswinberlin

Hey, maybe I'm a poser too...I don't see anything wrong with please help me (I might not use it as a title thought).

We've all gotta learn from somebody unless we're just here to tell everyone how great we are.

I just look at it as helping keep basic trouble shooting skills honed.

by marco136669

thank you for the support i never thought saying "please help" would create such a big fuss, i think some people dont believe in being polite these days.

by Member 19291532

Can you separate the upstairs segment and the downstairs segment? Are you on DHCP or static IPs?

I'd neet to know more about the topography - but if it doesn't sound like a DHCP network. If the downstairs isn't operating right and upstairs is doing fine...

My thought is that if upstairs is fine, and downstairs is bonkers, there is cabling problems downstairs. Is there a single drop upstairs, or are there separate drops to all the machines both downstairs and up? Are downstairs all in a single "block" on your switch and upstairs all on another block? I know you've swapped out your switch, so it isn't hardware at the switch level... which really only leaves drops... but if you haven't done this, do it:

My guess is all your drops were on certain ports... say, downstairs, ports 1 through 8... upstairs, port 8 through 16. You bought a new switch, and did you hook up the drops the same? That is, downstairs on port 1 through 8, upstairs port 1 through 16 (add your own appropriate numbers upstairs and down here).

Switch it. Put downstairs on 8 through 16 and upstairs on 1 through 8. Does upstairs still work fine and downstairs have a problem? If so, it isn't the switch or the cabling. If the problem *switched*, though... it is cabling, almost for certain being that you've already replaced the switch.

I think that is what I would be doing, if I were in your situation.

Good luck.

by marco136669

I removed all the connections which were not in use(meaning not connected to a PC) and the problem seem to have gone away, after i changed my server password there seem to be no problems and magically all the computers are working fine, so that is why i had to suspect that it was a hack attack from someone who knows the schools server password. if any problems arise again i will keep it posted here.

thank you

by marco136669

most computers are on DHCP as i had a problem sometime back with the ISA server and had to disable DHCP on some PC's so would it be a problem?

The entire school is connected with 7 switches and it never had any problems before but for safety like i have mentioned i removed all the connections which were not in use so that in case any socket is broken it shouldn't give any trouble and check the entire school for any physical damage but i couldn't find any, so the only thing that came to my mind was a hack attack, but i am still not sure what the exact problem was i am just great full that its working fine as i spend an entire night trying to figure out what the problem was and i couldn't come to an conclusion other than a hack attack.

Thank you

by Member 19291532

Well... my thought was that if you tried the method I suggested, and the problem persisted, that there was some sort of packet storm going on at the network layer that was causing some sort of segmentation of your network. It looks like a DoS attack - but being that it was splitting one geographic location from another... then you're wondering what single point of failure exists between locatio A and B (in this case, up and downstairs).

Glad to hear it cleared up, in any case. If you've got a network layer attack that isn't related to malware - then you've got a vunerability in either your OS platform or on some piece of hardware on your network. That is the next place to look if you want to make sure it doesn't happen again. Hardware patches, OS patches... and make sure all your AV engines and .dats are on their latest versions.

by darren95al

Hi according to me if your network is fail so some are main setting remove and after remove you will again do this setting i hope again make your network.

Thanks!!!!
msds software

by marco136669

Thank you so much for the help, my server is updated regularly and all the Anti Virus software's are updated regularly.

If any further problem arises i will be glad to ask you for help.

Thank you once again

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