请问这个是DOS攻击吗？

arbor

从apache的错误日志里面看到的，持续时间约半小时

[Sun Jan 20 10:41:37 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:39 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:41 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:43 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:45 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:47 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:49 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:51 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:54 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:55 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:57 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:41:59 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:01 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:03 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:05 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:07 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:09 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:15 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:17 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:19 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:21 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:23 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:25 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:27 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:29 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:31 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:33 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:35 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:37 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:39 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:41 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:43 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs
[Sun Jan 20 10:42:45 2008] [error] [client 61.135.166.229] File does not exist: /var/www/html/forum/bbs