From a client that you expect to use Pi-hole, run the following commands:
nslookup pi.hole
That should return your Pi-hole's IP, and that IP should also match that of the server at the start of the very same reply. If so, it confirms that your client is using Pi-hole as DNS server.
nslookup flurry.com 192.168.0.xx
Replace 192.168.0.xx
with your Pi-hole's actual IP address before executing.
That should return 0.0.0.0
with a default Pi-hole, which confirms your Pi-hole is blocking domains.