How to log http 404 error to a separate log file?

Apache Web Server:
how to log http 404 error to a separate log file and i do not want to log in access.log
please advice.

Please be MUCH more specific on what you are trying to do.

• What operating system are you using?
• Are you trying to write code in apache that will log 404 errors to a different log file than other errors?
• Are you trying to read web pages served by apache and you want to create a log file of 404 errors you encountered while accessing pages?
• What log file do you want to use?
• ...

1. What operating system are you using?
   Red Hat Enterprise Linux Server release 6.7 (Santiago)
2. Are you trying to write code in apache that will log 404 errors to a different log file than other errors?
   if any users hit wrong page, the apache webserver will server 404 page, it is captured in access_log by deafualt.
   Instead, i want to write in a separate file called Notfound.log
3. Are you trying to read web pages served by apache and you want to create a log file of 404 errors you encountered while accessing pages?
   yes
4. What log file do you want to use?
   i want to write in a separate file called Notfound.log