The lab adds a 1 GiB spare disk with a filesystem mounted at /data and fills most of it with one large file, as if you had run fallocate there. The mount lasts until the next reboot. It installs nginx if it's missing and puts a typo in /etc/nginx/nginx.conf, so nginx fails to start. Reset puts nginx back as it was.

Tasks

/data is nearly full. Find what fills it with df and du, as if you didn't know, and write the full path of the large file to /root/lab-answers/1.
nginx won't start. Find the error with systemctl status, journalctl -u nginx and nginx -t, fix it, and get nginx running (and starting at boot) again.
Put a wrong DNS server in the VM's network settings and diagnose the symptoms with ping and dig. Put it back. Not graded.
Install stress-ng, run stress-ng --cpu 2 --timeout 60 (or yes > /dev/null) and watch the load average in top. Not graded.
Give root a password, add a bad line to /etc/fstab, reboot, and recover from emergency mode. Do this only at the VM's console, and take a snapshot first. Not graded: the VM booting normally again is your check.

Hints

df -h, then du -xh --max-depth=1 /data | sort -h, one level deeper each time; du -a also shows files, and ls -la shows hidden ones.
nginx -t names the file and line. systemctl restart nginx, systemctl enable nginx, curl -s localhost | head.
resolvectl dns on Ubuntu; nmcli connection modify ... ipv4.dns on the RHEL family.
stress-ng is in the RHEL family's AppStream and Ubuntu's universe.
In emergency mode, mount -o remount,rw /, fix /etc/fstab, systemctl daemon-reload, mount -a, then reboot.