Reduce DNS lookups

Before adding my site to Cloudflare, I tested my site on GTMatrix, Google, and Pingdom. After adding my site on Cloudflare using the CNAME record from my web hosting cPanel plugin, I again check my website. Here are the different speed test result on Pingdom,

Before,
F - Make fewer HTTP requests
F - Use cookie-free domains
F - Add Expires headers
C - Compress components with gzip
B- Avoid URL redirects
A - Reduce DNS lookups
A - Avoid empty src or href

After,
F - Make fewer HTTP requests
F - Use cookie-free domains
D - Add Expires headers
F - Compress components with gzip:small_red_triangle_down:
B- Avoid URL redirects
F - Reduce DNS lookups:small_red_triangle_down:
A - Avoid empty src or href

I don’t know why DNS lookups score down. How can I solve this problem? I searched everywhere, but I couldn’t find the right solution for my problem.