ping api.soundcloud.com时没问题：
ping api.soundcloud.com
PING d3ad8414wy4gwn.cloudfront.net (52.85.73.227) 56(84) bytes of data.
64字节来自server-52-85-73-227.lhr3.r.cloudfront.net（52.85.73.227）：icmp_seq = 1 ttl = 247 time = 4.06 ms
但是什么时候在HTTP上进行通信：
curl http://api.soundcloud.com/
我（很长一段时间）得到了这个回复：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML><HEAD><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<TITLE>ERROR: The request could not be satisfied</TITLE>
</HEAD><BODY>
<H1>ERROR</H1>
<H2>The request could not be satisfied.</H2>
<HR noshade size="1px">
CloudFront attempted to establish a connection with the origin, but either the attempt failed or the origin closed the connection.
<BR clear="all">
<HR noshade size="1px">
<PRE>
Generated by cloudfront (CloudFront)
Request ID: 4fFcKB1pjCSFOLlNJcBpG36rPSRPqb1eHUSzUkPbDqyZD2HWSdKBfw==
</PRE>
<ADDRESS>
</ADDRESS>
</BODY></HTML>
我从未得到回应。问题仅出现在我的服务器上（从另一个IP工作），在178.32.223.76公共IP地址后面。
我的服务器是黑名单？怎么知道？我该怎么办？