I have a question about why my DNS settings got messed up. I've fixed the issue (I think), but I'm curious as to why it happened. My Linux Mint 18.3 laptop had been working flawlessly. I recently installed PulseSecure to VPN into my university's secure network from off campus. That worked great for several days. Then all of a sudden, my internet stopped working at home. The wireless was connected, but it could never resolve a host. After some Googling (from another computer), I figured out that I could ping my gateway, some IP addresses, and Google DNS 22.214.171.124., but not website names.
I followed some internet advice and checked my resolv.conf file and saw
~ $ cat /etc/resolv.conf search colostate.edu nameserver 126.96.36.199 nameserver 188.8.131.52
Those are CSU internal IP addresses. I added two lines to my resolv.conf
nameserver 184.108.40.206 nameserver 220.127.116.11
Then, to make sure the changes stuck, I opened my network connections for my home internet, went to the IPv4 Settings, changed Method to Automatic DHC addresses only, and set DNS server to 18.104.22.168 (again per internet advice I found). Things are working fine now, for the moment, although they feel a bit sluggish.
I noticed that, when I logged in to my VPN via pulse secure just now, resolv.conf is back to its original form
search colostate.edu nameserver 22.214.171.124 nameserver 126.96.36.199
like it was just overwritten. I'm concerned that my internet now will no longer work and I'll have to fix this every time.