A question about always_direct

[Gemmy <chenryn@xxxxxxx>]

 I have a cache server running squid2.7.9. I wrote the follow
configurations:
acl Safe_ports port 80
acl Domain dstdomain .china.com
acl Domain dstdomain .haiyang2012.com
http_access allow Safe_ports Domain
http_access deny all
cache_peer 10.168.168.13 parent 80 0 no-query no-netdb-exchange
originserver round-robin
cache_peer 10.168.170.14 parent 80 0 no-query no-netdb-exchange
originserver round-robin
cache_peer_access 10.168.168.13 allow Domain
cache_peer_access 10.168.170.14 allow Domain
always_direct allow !Domain

When I request a url like "http://military.china.com/zh_cn/etc/endpage
/showPic.html"，I can see "HTTP/1.0 OK" and so on.
But when I request a url like
"http://military.china.com/zh_cn/etc/endpage/showPic.html?http://image.tuku.china.com/tuku.military.china.com/military//pic/2010-09-20/b12a1145-dd40-4fcb-8ce0-1372ac934f66.jpg";(this
url just redirect request into
"http://image.tuku.china.com/tuku.military.china.com/military//pic/2010-09-20/b12a1145-dd40-4fcb-8ce0-1372ac934f66.jpg";),the
squid response a "504 time out"!
I strace the squid process and see that when squid handle the request
having a "?", he donot back to the ip defined in cache_peer but the ip
resolved by dnssever which is himself!
I change the conf as "never_direct allow all",problem solved.
But I still think that the conf using "always_direct" is right, why its
not take effect？？