IPv4で接続したのか、それともIPv6で接続したのかは、あなたのIPアドレスを示すREMOTE_ADDRの項で判別できます。
REMOTE_ADDR: 3.80.224.52 (AF_INET) REMOTE_HOST: REMOTE_PORT: 52300 SERVER_PROTOCOL: HTTP/1.1 REQUEST_METHOD: GET REQUEST_URI: /yousentme.php QUERY_STRING: HTTP_ACCEPT: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 HTTP_ACCEPT_CHARSET: HTTP_ACCEPT_ENCODING: gzip HTTP_ACCEPT_LANGUAGE: en-US,en;q=0.5 HTTP_CONNECTION: Keep-Alive HTTP_HOST: katsu.watanabe.name HTTP_REFERER: HTTP_USER_AGENT: CCBot/2.0 (https://commoncrawl.org/faq/) REQUEST_TIME_FLOAT: 1555676109.5391 (2019-04-19T21:15:09+09:00)