ktDNS stands for kotori-DNS server.
This is a simple implementation of DNS servers, only itsukakotori.moe and google.com is supported, and I won't add any other DNS records in the future.
run ktDNS.py at root privilege for this need to bind on 53 port
sudo python3 ktDNS.py
Then use dig command to see if this take effect (specify the DNS server to 127.0.0.1)
dig itsukakotori.moe @127.0.0.1
Execption handling
Get rid of global variable zone