Its an Access Log entry, though I’ve never seen one formatted like that. Usually the log entry (at least on Apache Servers) starts with “GET” or “HEAD.” It tells you information about who is visiting your site and what they were doing.
In your example, the visitor’s IP Address was 138.180.167.83
He visited on 5/17/2003 at 6:45 pm (6:45 in the timezone of your server)
I believe 220 and 200 are the codes for a successful connection, meaning your server sent the full web page to the visitor
GET Default.asp means that the page “default.asp” was the page that was requested by the visitor.
For my site, I mainly use the access log to see what worms are trying to gain access to the server, and if any of my pages are not being sent properly.
Here’s a definition of what an access log is that I grabbed from searchSecurity.com: