After connecting a VPN on Linux (my case an Ubuntu) that resolv.conf is not updated and you can’t resolve names from that network as expected.
After searching a bit I found this website that gave me a solution.
You can check in detail here: https://dev.to/setevoy/arch-linux-openvpn–resolvconf-is-not-updated-2470
After connection to the VPN has been performed, we can observe that resolv.conf hasn’t been updated.
$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.
nameserver 127.0.0.53
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Modify your opvn file and these new lines (bottom is fine):
...
script-security 2
up /etc/openvpn/update-resolv-conf
down /etc/openvpn/update-resolv-conf
Restart your VPN connection and check again your resolv.conf file.
$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.
nameserver 10.11.0.2
nameserver 127.0.0.53
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After terminating your VPN connection, resolv.conf file will be restored to its previous state.