centos7 – Domain names not resolving on CentOS webserver

I have a small webhosting VPS running CentOS Linux 7.9.2009 (Core).

I’m also running Plesk Obsidian Version 18.0.52

Here is my /etc/resolv.conf file:

nameserver 1.1.1.1
nameserver 8.8.4.4
nameserver 71.19.155.120
nameserver 71.19.155.215

(The last 2 nameservers are provided by my VPS host)

From the CLI I cannot dig, ping, traceroute, etc… even my own hostname.

I noticed this yesterday and now my clients are reporting various issues that I imagine are related (emails stuck in queue, can’t log into local WordPress installations, WooCommerce issues).

# ping google.ca
ping: google.ca: Name or service not known

and

# dig www.Google.com @8.8.8.8

; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.8 <<>> www.Google.com @8.8.8.8
;; global options: +cmd
;; connection timed out; no servers could be reached

What the heck is going on?