Strange DNS Issue
I have a problem and solution, but need help understanding the cause. I have a laptop which is hardwired into our network with the wireless turned off. I set the static IP settings as follows
DNS: 192.168.0.11, 192.168.1.3
I am trying to contact device horstj-7 (192.168.1.78). The device itself has the same gateway and DNS, but a mask of 255.255.240.0.
I can ping 192.168.1.78 with now problems. I can even do a ping /a and it returns the correct hostname. However, pinging horstj-7 returns "Ping request could not find host horstj-7..."
Changing the mask to the 240 subnet allows me to ping the hostname with no problems. Being curious, I changed to the 254 subnet. This should still work as my device is in the 0 range and the target is a 1. However, I can ping the IP with no problem, but not the hostname. Back to the 240 subnet and everything works fine.
I duplicated this same problem with another laptop. I noticed that there was no DNS entry in either DC for horstj-7. I added a Host (A) record, waited a few minutes, and did a force update on the laptop. It now works correctly regardless of the subnet.
This was obviously a DNS issue, but what could possibly cause the behavior where everything is fine if you are on ONE specific subnet mask? I would have thought that a DNS problem would be prevalent regardless of the mask.
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