What role does DNS play in a curl error 7 when connecting to port 443, and how can I test it?

DNS translates domain names (like example.com) into IP addresses. If DNS resolution fails, curl can't connect. Use `nslookup example.com` or `dig example.com` to verify the domain resolves to a valid IP address. If it doesn't, the issue lies with your DNS server settings. Try using a public DNS server like Google's (8.8.8.8 and 8.8.4.4) or Cloudflare's (1.1.1.1).