: File does not exist from wacky websites? Our LAMPs website has been running slow as of late, I suspect its a SQL problem but I want to check all the logs. Can somebody explain what the following

Our LAMPs website has been running slow as of late, I suspect its a SQL problem but I want to check all the logs. Can somebody explain what the following log means, and give some insight if it is a performance/security problem?

[root@ip-10-225-131-71 logs]# tail -9 error_log
[Thu Jun 25 00:01:33 2015] [error] [client 172.82.141.249] File does not exist: /var/www/html/tt, referer: www.xe.com/xecurrencydata/ [Thu Jun 25 00:01:33 2015] [error] [client 172.82.141.117] File does not exist: /var/www/html/tt, referer: www.evite.com/gallery/category/holiday_party/ [Thu Jun 25 00:01:33 2015] [error] [client 45.43.208.201] File does not exist: /var/www/html/tt, referer: www.evite.com/profile/events [Thu Jun 25 00:01:33 2015] [error] [client 45.43.208.92] File does not exist: /var/www/html/tt, referer: www.evite.com/gallery/category/hostess_party/ [Thu Jun 25 00:01:33 2015] [error] [client 45.43.206.167] File does not exist: /var/www/html/tt, referer: www.evite.com/gallery/category/brunch_lunch/ [Thu Jun 25 00:01:33 2015] [error] [client 45.43.206.76] File does not exist: /var/www/html/tt, referer: www.evite.com/profile/edit [Thu Jun 25 00:01:33 2015] [error] [client 172.82.141.55] File does not exist: /var/www/html/tt, referer: www.xe.com/useourcontent.php [Thu Jun 25 00:01:33 2015] [error] [client 172.82.141.6] File does not exist: /var/www/html/tt, referer: www.xe.com/es/ [Thu Jun 25 00:01:33 2015] [error] [client 162.213.31.80] File does not exist: /var/www/html/tt, referer: www.evite.com/gallery/category/birthday_milestones/

From my understanding, websites are trying to access files that don't exist on our webserver?