Robert Scoble says that MSDN is turning off full-text RSS feeds because they eat too much bandwidth. I left a comment suggesting they turn on support for conditional HTTP GET, and I wanted to give some real-world numbers for the amount of bandwidth this saves, so I checked my current access log:
abe@fettig:~$ grep "GET /xml/rss2.xml" \
/var/log/apache/fettig.net-access.log \
| cut -d ' ' -f 9 | sort | uniq -c
763 200
5069 304
That’s really impressive. Out of 5543 requests, 4831 resulted in a 304 ‘unchanged’ response (meaning that the actual file wasn’t downloaded): an 87% bandwidth savings. The majority of feed readers are behaving like they should, checking to make sure the file has changed before they download it.