In the Forefront TMG Management console tree, select Logs and Reports.

In the details pane, select the Logging tab.

Click Start Query.

In the log that appears, right-click any column heading, and then click Add/Remove Columns. Use Move Up and Move Down to specify where the information should appear in the log headings.

In the Add/Remove Columns dialog box, select the Filter Information column, click Add, and then click OK. The following information may appear in the Filter Information column:

• Client—Indicates whether compression is enabled between Forefront TMG and the client, as well as whether the client requested compression. If both conditions are true, this will show Y (yes). If either condition is false, this will show N (no).
  
  
• Server—Indicates whether Forefront TMG requested compression from the Web server.
  
  
• Cache—Indicates whether content was served to the client from the cache. This sometimes mistakenly indicates Y (yes).
  
  
• Compression Rate—The amount of compression that has taken place on a specific response. This is calculated as:
  (size of original response - size of compressed response) x 100/size of original response
  
  
• Decompression Rate—The amount of decompression that has taken place on a specific response. This is calculated as:
  compressed output x 100/decompressed output
  
  

Note:
A simple way to check whether compression is operational is to verify if either the compression rate or decompression rate is greater than 0.