There are mainly 2 types of logs in Apache Web Server. By default Error log is enabled/ON.
 

1. Error log
   
   LOGLEVEL SIGNIFICANCE OF ERROR
   
   emerg System is unstable
   alert Immediate action required
   crit Critical error
   error Non-critical error
   warn (Default) Warning
   notice Normal but significant
   info Informational
   debug Debug level
   
    
2. Access Log. (Transactions between Client and Manager will be logged)
   
   There are two Access log level types: Common and Combined
   
   How to enable the Access log:
   1. Navigate to:
      
      C:\Program Files\Symantec\Symantec Protection Center\apache\conf
      
       
   2. Open httpd.conf in Notepad
   3. Search for/locate the following line in the file:
      
      #CustomLog "logs/access.log" combined
      
       
   4. Remove the # so that the line reads as follows:
      
      CustomLog "logs/access.log" combined
      
       
   5. Restart Symantec Protection Center Webserver Services:
      1. Click Start, then Run
      2. Type the following:
         
         services.msc
         
          
      3. Click OK
      4. Right-click on Symantec Protection Center Webserver
      5. Click Restart
      6. Click Yes
   
   
   
   

The error.log and access.log can be found in the following location:

C:\Program Files\Symantec\Symantec Protection Center\apache\logs

References
http://www.devshed.com/c/a/Apache/Logging-in-Apache/

http://httpd.apache.org/docs/2.0/logs.html


Technical Information
-Common log

Output:-
e.g.
127.0.0.1 - harry [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326

-Combined log

Output:-
e.g.
127.0.0.1 - harry [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326 "http://www.example.com/start.html" "Mozilla/4.08 [en] (Win98; I ;Nav)"

This format is exactly the same as the Common Log Format, with the addition of two more fields. Each of the additional fields uses the percent-directive %{header}i, where header can be any HTTP request header.