这个问题困扰了我好几天。我会尽力提供尽可能多的信息，但如果需要更多详细信息，请随时询问。
我在 NAT 后面有 2 个虚拟机，192.168.0.100 和 192.168.0.102，都运行 Ubuntu 11.04 x64。第一个虚拟机映射到外部，是我们的 Web 服务器，安装了一个 Apache/2.2.17，带有多个 vhost 来提供静态内容，还有 mod_jk 用于负载平衡。第二个虚拟机安装了 tomcat 7，带有几个 J2EE REST Web 服务，但没有 apache - 请求预计将直接从 .100 apache 传递到 .102 tomcat。我打算准备一个 tomcat 集群环境。
我的问题：请求毫无问题地到达 192.168.0.100，但随后需要大约...100 秒数据实际到达 .102 - 那时 apache 已经超时，但 tomcat 接收并处理请求非常正常。使用 mod_jk、mod_proxy 或 mod_ajp_proxy 时都会发生这种情况。不知道为什么，因为两台机器都没有防火墙，所以都可以 ping 通 - 更重要的是，有 NFS 共享活动工作正常 - 并且 mod_proxy 体验显示直接来自 .100 的请求可以正常处理。
此外，更糟糕的是，我们的办公网络也设置了类似的环境。一切都运行良好。-_- 唯一的区别是什么？我们的办公室没有 IP 转换，所有事情都通过内部地址进行 - 不知道这是否相关。
一些配置：
Apache 虚拟主机：
<VirtualHost *:80>
ServerAdmin webmaster@localhost
DocumentRoot /var/www/
ServerName www.example.com
ProxyRequests Off
<Proxy *>
Options Indexes FollowSymLinks MultiViews
AllowOverride all
Order allow,deny
allow from all
</Proxy>
ProxyPass /bork http://192.168.0.102:8080/bork
ProxyPassReverse /bork http://192.168.0.102:8080/bork
LogLevel debug
CustomLog ${APACHE_LOG_DIR}/api_access.log combined
ErrorLog ${APACHE_LOG_DIR}/api_error.log
</VirtualHost>
Tomcat 连接器
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" />
<Connector port="8009"
enableLookups="false"
redirectPort="8443"
protocol="AJP/1.3"
/>
这是来自 apache 的调试日志，来自使用 mod_proxy_ajp 的测试。mod_proxy 中的行为几乎相同，至少在延迟方面。请注意，当日志再次开始更新时，tomcat 最终会接收并处理请求：
[Sun May 06 14:40:33 2012] [debug] proxy_util.c(1506): [client 188.81.234.2] proxy: ajp: found worker ajp://192.168.0.102:8008/bork for ajp://192.168.0.102:8008/bork/SSOIdentityProviderSoap
[Sun May 06 14:40:33 2012] [debug] mod_proxy.c(1015): Running scheme ajp handler (attempt 0)
[Sun May 06 14:40:33 2012] [debug] mod_proxy_ajp.c(661): proxy: AJP: serving URL ajp://192.168.0.102:8008/bork/SSOIdentityProviderSoap
[Sun May 06 14:40:33 2012] [debug] proxy_util.c(2011): proxy: AJP: has acquired connection for (192.168.0.102)
[Sun May 06 14:40:33 2012] [debug] proxy_util.c(2067): proxy: connecting ajp://192.168.0.102:8008/bork/SSOIdentityProviderSoap to 192.168.0.102:8008
[Sun May 06 14:40:33 2012] [debug] proxy_util.c(2193): proxy: connected /bork/SSOIdentityProviderSoap to 192.168.0.102:8008
[Sun May 06 14:40:33 2012] [debug] proxy_util.c(2444): proxy: AJP: fam 2 socket created to connect to 192.168.0.102
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(224): Into ajp_marshal_into_msgb
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(290): ajp_marshal_into_msgb: Header[0] [Accept-Encoding] = [gzip,deflate]
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(290): ajp_marshal_into_msgb: Header[1] [Content-Type] = [text/xml;charset=UTF-8]
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(290): ajp_marshal_into_msgb: Header[2] [SOAPAction] = [""]
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(290): ajp_marshal_into_msgb: Header[3] [User-Agent] = [Jakarta Commons-HttpClient/3.1]
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(290): ajp_marshal_into_msgb: Header[4] [Host] = [www.example.com]
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(290): ajp_marshal_into_msgb: Header[5] [Content-Length] = [520]
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(450): ajp_marshal_into_msgb: Done
[Sun May 06 14:40:33 2012] [debug] mod_proxy_ajp.c(267): proxy: APR_BUCKET_IS_EOS
[Sun May 06 14:40:33 2012] [debug] mod_proxy_ajp.c(272): proxy: data to read (max 8186 at 4)
[Sun May 06 14:40:33 2012] [debug] mod_proxy_ajp.c(287): proxy: got 520 bytes of data
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(687): ajp_read_header: ajp_ilink_received 06
[Sun May 06 14:40:33 2012] [debug] ajp_header.c(697): ajp_parse_type: got 06
[Sun May 06 14:40:37 2012] [debug] proxy_util.c(1818): proxy: grabbed scoreboard slot 2 in child 5916 for worker ajp://192.168.0.100:8008/coding
[Sun May 06 14:40:37 2012] [debug] proxy_util.c(1837): proxy: worker ajp://192.168.0.100:8008/coding already initialized
[Sun May 06 14:40:37 2012] [debug] proxy_util.c(1934): proxy: initialized single connection worker 2 in child 5916 for (192.168.0.100)
[Sun May 06 14:40:37 2012] [debug] proxy_util.c(1818): proxy: grabbed scoreboard slot 3 in child 5916 for worker http://192.168.0.102:8080
[Sun May 06 14:40:37 2012] [debug] proxy_util.c(1837): proxy: worker http://192.168.0.102:8080 already initialized
[Sun May 06 14:40:37 2012] [debug] proxy_util.c(1934): proxy: initialized single connection worker 3 in child 5916 for (192.168.0.102)
[Sun May 06 14:40:37 2012] [debug] proxy_util.c(1818): proxy: grabbed scoreboard slot 4 in child 5916 for worker ajp://192.168.0.102:8008/bork
[Sun May 06 14:40:37 2012] [debug] proxy_util.c(1837): proxy: worker ajp://192.168.0.102:8008/bork already initialized
[Sun May 06 14:40:37 2012] [debug] proxy_util.c(1934): proxy: initialized single connection worker 4 in child 5916 for (192.168.0.102)
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1934): proxy: initialized single connection worker 2 in child 5918 for (192.168.0.100)
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1818): proxy: grabbed scoreboard slot 3 in child 5918 for worker http://192.168.0.102:8080
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1837): proxy: worker http://192.168.0.102:8080 already initialized
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1934): proxy: initialized single connection worker 3 in child 5918 for (192.168.0.102)
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1818): proxy: grabbed scoreboard slot 4 in child 5918 for worker ajp://192.168.0.102:8008/bork
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1837): proxy: worker ajp://192.168.0.102:8008/bork already initialized
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1934): proxy: initialized single connection worker 4 in child 5918 for (192.168.0.102)
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1818): proxy: grabbed scoreboard slot 2 in child 5917 for worker ajp://192.168.0.100:8008/coding
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1837): proxy: worker ajp://192.168.0.100:8008/coding already initialized
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1934): proxy: initialized single connection worker 2 in child 5917 for (192.168.0.100)
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1818): proxy: grabbed scoreboard slot 3 in child 5917 for worker http://192.168.0.102:8080
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1837): proxy: worker http://192.168.0.102:8080 already initialized
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1934): proxy: initialized single connection worker 3 in child 5917 for (192.168.0.102)
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1818): proxy: grabbed scoreboard slot 4 in child 5917 for worker ajp://192.168.0.102:8008/bork
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1837): proxy: worker ajp://192.168.0.102:8008/bork already initialized
[Sun May 06 14:40:38 2012] [debug] proxy_util.c(1934): proxy: initialized single connection worker 4 in child 5917 for (192.168.0.102)
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(687): ajp_read_header: ajp_ilink_received 04
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(697): ajp_parse_type: got 04
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(516): ajp_unmarshal_response: status = 200
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(537): ajp_unmarshal_response: Number of headers is = 1
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(599): ajp_unmarshal_response: Header[0] [Content-Type] = [text/xml;charset=utf-8]
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(609): ajp_unmarshal_response: ap_set_content_type done
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(687): ajp_read_header: ajp_ilink_received 03
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(697): ajp_parse_type: got 03
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(687): ajp_read_header: ajp_ilink_received 03
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(697): ajp_parse_type: got 03
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(687): ajp_read_header: ajp_ilink_received 05
[Sun May 06 14:42:09 2012] [debug] ajp_header.c(697): ajp_parse_type: got 05
[Sun May 06 14:42:09 2012] [debug] mod_deflate.c(615): [client 188.81.234.2] Zlib: Compressed 447 to 255 : URL /bork/SSOIdentityProviderSoap
[Sun May 06 14:42:09 2012] [debug] mod_proxy_ajp.c(570): proxy: got response from (null) (192.168.0.102)
[Sun May 06 14:42:09 2012] [debug] proxy_util.c(2029): proxy: AJP: has released connection for (192.168.0.102)
[Sun May 06 14:42:09 2012] [info] [client 188.81.234.2] Request body read timeout
想知道是否有人可以提供一些建议，甚至指出任何可怕的配置错误？提前谢谢！
答案1
这几乎肯定是 DNS。检查从 .102 到 .100 的反向 DNS 查找时间。