The domain name for the pi.hole/admin web page is unreachable

I have successfully setup the pi-hole DNS server on pi and it seems to be working. I also set up the lighttpd web server and I can reach it using /admin. However, I cannot reach it using any of the three methods shown here: How do I access Pi-hole's Dashboard admin interface? which were posted by jacob.salmela as follows:

There are three ways to get to the admin dashboard from your Web browser:
http:/pi.hole/admin (when using Pi-hole as your DNS server)
http://pi.hole/ 88.8k (when using Pi-hole as your DNS server)

I tried nslookup as shown below:
~$ nslookup pi.hole

** server can't find pi.hole: NXDOMAIN
It seems that the domain name resolution of of pi.hole is not being returned by pi-hole itself.

How can this be fixed? Thank you!

The output of pihole -d has been uploaded to tricorder. Here is the token:

Thanks again.

That's not the Pi-hole server, that's probably systemd-resolved.

What IP address are you using?