httpd: Could not reliably determine the server's fully qualified domain name using 127.0.0.1 for ServerName Apache

apachectl -k start
apachectl -k stop
をすると以下のエラーが発生

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httpd: apr_sockaddr_info_get() failed for サーバ名
httpd: Could not reliably determine the server s fully qualified domain name using 127.0.0.1 for ServerName
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対応は、httpd.confに以下を追加
ServerName サーバー名:80