Correct DNS Record configuration

I would like to ask you about a few things about configuration DNS records.

I have domain, let's say: mydomain.com and we have a server on: publicIP:port

I want add subdomain, let's say test.

So I added DNS record type URL Frame with address http://publicIP:port/ but then in ngix logs I get:

http header: "Host: publicIP:port"
10786 2018/02/21 10:21:19 [debug] 24499#24499: *5 http header: "Connection: keep-alive"
10787 2018/02/21 10:21:19 [debug] 24499#24499: *5 http header: "Pragma: no-cache"
10788 2018/02/21 10:21:19 [debug] 24499#24499: *5 http header: "Cache-Control: no-cache"
10789 2018/02/21 10:21:19 [debug] 24499#24499: *5 http header: "Upgrade-Insecure-Requests: 1"
10790 2018/02/21 10:21:19 [debug] 24499#24499: *5 http header: "User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36"
10791 2018/02/21 10:21:19 [debug] 24499#24499: 5 http header: "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,/*;q=0.8"
10792 2018/02/21 10:21:19 [debug] 24499#24499: *5 http header: "Referer: http://test.mydomain.com/"
10793 2018/02/21 10:21:19 [debug] 24499#24499: *5 http header: "Accept-Encoding: gzip, deflate"
10794 2018/02/21 10:21:19 [debug] 24499#24499: *5 posix_memalign: 0000563A91913770:4096 @16
10795 2018/02/21 10:21:19 [debug] 24499#24499: *5 http header: "Accept-Language: pl-PL,pl;q=0.9,en-US;q=0.8,en;q=0.7"

I have a name of subdomain in referer header field. Is it right configuration? Or it's existing way to configure it way where I can get subdomain in Host field? It's connected with my next question about nginx configuration. When I have subdomain name in referer then nginx doesn't recognize it when I'm using server names.