Hello, I have been trying to follow all the help documnts on how to setup the script on a Raspberry Pi, but it will not work

Command I am using:
echo url="https://api.dynu.com/nic/update?username=USERNAME&password=PASSWORD" | curl -k -o ~/dynudns/dynu.log -K -

Message I get
pi@piVPN:~/dynudns $ sudo echo url="https://api.dynu.com/nic/update?username=username&password=password" | curl -k -o /home/pi/dynu.log -K -
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0curl: (6) Could not resolve host: api.dynu.com

the resulting dynu.log is empty.

Can you pelase help, thanks

ddclient works on my pi zero w.