DNS requests are made to your DNS server on port 53.
The HTTP request in your Internet browser, if proxy is enabled, is forwarded to your proxy server. The proxy server will allow/prevent connection to the http web request.
Open up your command prompt and type in nslookup www.twing.com
You will see that a dns request/response is sent/received from your DNS server that is configured through your static or dhcp settings.
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