Friday, October 28, 2016

Work Life: Dueling DHCP Servers (DNS Errors, Unauthenticated Networks)


Heya!
  Today, I visited a school that was having issues with some of their computers in specific locations. Usually, when a district calls with something like that, we start in the room(s) where the trouble seems to be and work our way outward from there. In this case, there was an elementary lab in which all but one row of computers was throwing up some weird errors.

The machines are running Windows 7, and the network icon in the system tray would change from the standard computer to one with a yellow warning triangle. Then, a message would pop up stating that the computer was connected to the local network but was "unauthenticated." Other computers showed the normal computer icon but when they tried to get online, the browser would throw up messages about unresolved DNS issues, etc.

When the tech would check the IP address on any of the errant machines, the initial address would show the local network scheme. However, when the warning icon appeared, an ipconfig revealed the address had been changed to a 192.168 range.

That range, as many of you know, is where things like wifi routers like to live. So, I asked about switches, other network equipment, etc.  The tech had put in a new switch (new to them) that they had received from another district. Since the "new" switch was an HP Procurve, I thought maybe something was going on there. Plus, that had been the most recent change the tech could remember at the time.

I removed the switch and was about to put in another switch, the tech came in and told me that she remembered they were testing their new Kajeet-based MiFi hotspots at about the same time everything went wacko.

Instantly, we had our answer. You see, when they were testing the hotspots, they were using them in tethered mode, meaning they hooked up the device to the computer via USB cable and let the computer use that as the connection. Well, the hotspot is set up to hand out IP addresses (DHCP). Normally, this is not an issue - the computer gets an IP address and life goes on.

Here is the rub: If the computer in question is ALSO connected to the local network (via Ethernet cable, for example), the hotspot actually communicates down that wired line through the computer it is connected to. So... The hotspot was answering DHCP requests from certain computers on the network. Of course, I want to know why only those specific computers and not, say, computers spread throughout the district. Unfortunately, we may never know the answer because all of the trouble took place the day before I arrived and the hotspots were already disbursed.

So, in a nutshell (the TL;DR version, I suppose you kids would say these days): Erratic computer connectivity might be blamed on multiple DHCP devices on your network. Check for Wireless Routers, tethered hotspots, internet connection sharing, etc.

Monday, October 10, 2016

Back to Blogging

https://www.flickr.com/photos/carbonnyc/3909445371

Heya! It's time to do some housecleaning. I don't know how many folks check this blog to see my newly posted Youtube videos. But, I am going to change those posts on here so I can get back to making this a blog and not just a place to showcase my latest videos.

When I first start this blog, it was so I could have a place to keep track of certain things I figured I would forget. Then, it grew into a proper blog. Then, somewhere along the way, I quit writing and started simply posting the videos, Instagrams, etc from those other sites and basically quit blogging at all.

I'm not about that. Not anymore, anyway. I'd like to get back into blogging and back into what this site was meant for: a place I could express myself.

Now, I am going to tie in my gaming, etc because I am hoping to make this site a place where I can talk about the games I am playing or why I did/do certain things in my videos.

I think I am also going to have a link on here at the top that lists all the suggestions folks are making on the Youtube channel so everyone can see which ones I've done and which are yet to be recorded. I think that would be fun to keep track of online! I dunno, we'll see.

So, for my long-time readers, THANK YOU for sticking around and checking things out.  If you're new here, THANK YOU for coming by to see what PoppedInMyHead is all about!

I will still post the videos I've done, but now they will have a bit of backstory or explanation or some kind of reason for being here.

In the meantime, be sure to check out my videos: https://www.youtube.com/davidinark/

And, thanks for stopping by!

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