为什么curl同一网站一会200一会404

[root@Kry123 ~]# curl -x192.168.0.123:80 -I www.kry.com/forum.php
HTTP/1.1 404 Not Found
Date: Tue, 14 Jun 2016 08:02:53 GMT
Server: Apache/2.4.20 (Unix)
Content-Type: text/html; charset=iso-8859-1

[root@Kry123 ~]# curl -x192.168.0.123:80 -I www.kry.com/forum.php
HTTP/1.1 200 OK
Date: Tue, 14 Jun 2016 08:02:55 GMT
Server: Apache/2.4.20 (Unix) PHP/5.6.22
X-Powered-By: PHP/5.6.22
Set-Cookie: 4qfN_2132_saltkey=iEuSfRO4; expires=Thu, 14-Jul-2016 08:02:55 GMT; Max-Age=2592000; path=/; httponly
Set-Cookie: 4qfN_2132_lastvisit=1465887775; expires=Thu, 14-Jul-2016 08:02:55 GMT; Max-Age=2592000; path=/
Set-Cookie: 4qfN_2132_sid=P2cW2Q; expires=Wed, 15-Jun-2016 08:02:55 GMT; Max-Age=86400; path=/
Set-Cookie: 4qfN_2132_lastact=1465891375%09forum.php%09; expires=Wed, 15-Jun-2016 08:02:55 GMT; Max-Age=86400; path=/
Set-Cookie: 4qfN_2132_onlineusernum=2; expires=Tue, 14-Jun-2016 08:07:55 GMT; Max-Age=300; path=/
Set-Cookie: 4qfN_2132_sid=P2cW2Q; expires=Wed, 15-Jun-2016 08:02:55 GMT; Max-Age=86400; path=/
Cache-Control: max-age=0
Expires: Tue, 14 Jun 2016 08:02:55 GMT
Content-Type: text/html; charset=gbk

[root@Kry123 ~]# curl -x192.168.0.123:80 -I www.kry.com/forum.php
HTTP/1.1 404 Not Found
Date: Tue, 14 Jun 2016 08:04:03 GMT
Server: Apache/2.4.20 (Unix)
Content-Type: text/html; charset=iso-8859-1

[root@Kry123 ~]# curl -x192.168.0.123:80 -I www.kry.com/forum.php
HTTP/1.1 200 OK
Date: Tue, 14 Jun 2016 08:04:07 GMT
Server: Apache/2.4.20 (Unix) PHP/5.6.22
X-Powered-By: PHP/5.6.22
Set-Cookie: 4qfN_2132_saltkey=BCXQQCCx; expires=Thu, 14-Jul-2016 08:04:07 GMT; Max-Age=2592000; path=/; httponly
Set-Cookie: 4qfN_2132_lastvisit=1465887847; expires=Thu, 14-Jul-2016 08:04:07 GMT; Max-Age=2592000; path=/
Set-Cookie: 4qfN_2132_sid=Gxa4x9; expires=Wed, 15-Jun-2016 08:04:07 GMT; Max-Age=86400; path=/
Set-Cookie: 4qfN_2132_lastact=1465891447%09forum.php%09; expires=Wed, 15-Jun-2016 08:04:07 GMT; Max-Age=86400; path=/
Set-Cookie: 4qfN_2132_onlineusernum=2; expires=Tue, 14-Jun-2016 08:09:07 GMT; Max-Age=300; path=/
Set-Cookie: 4qfN_2132_sid=Gxa4x9; expires=Wed, 15-Jun-2016 08:04:07 GMT; Max-Age=86400; path=/
Cache-Control: max-age=0
Expires: Tue, 14 Jun 2016 08:04:07 GMT
Content-Type: text/html; charset=gbk