IIS 5 Administration - HTTP Headers Tab
The HTTP headers
tab is one of the places where you can do some serious tuning of your web
site, as well as enabling a huge number of other, special features.
Enable Content Expiration
The first box on this screen allows you to control if and how long items are stored in cache memory. Proxy servers, browsers and other devices have the ability to improve performance by storing copies of objects for a period of time. These devices make educated guesses about how long to keep their copies of your pages and graphics around. You can help them out by specifying exactly how long you want those copies kept.
What are the advantages of this? Well, you could have a very dynamic page which changes often; in that instance, you might set the document to expire immediately. This requests that proxy servers and browsers reload a new copy each time. On the other hand, you might have an "images" directory which never changes. You can improve performance by setting it to expire less often (even as long as years).
It is far better to use HTTP headers than Meta tags to control various HTTP functions. Most proxy servers and internet caches do not read HTML code to determine if there are Meta tags present; they do, however, read the HTTP headers.
It is important to note that these HTTP headers are only valid for browsers and servers using HTTP 1.1. Most of the headers are not supported by HTTP 1.0.
- Expire Immediately
- Causes proxy servers, browsers and internet cache's to load a fresh copy every single time the document or resource is requested.
- Expire after
- Set the number of minutes, hour or days which the resource is valid. New copies will be loaded after the time period has passed.
- Expire on
- This informs cache's that the resource is to expire precisely on a specific date and time.
Custom HTTP
Headers
This box allows you to add special or custom HTTP headers. You may enter any of the following values (and anything else defined in the HTTP 1.0 and 1.1 specifications).
- max-age
- This header field allows you to specify the number of seconds that an object will be considered fresh. Enter "max-age" as the name and the number of seconds as the value.
- s-maxage
- This is the same as "max-age" except that it applies only to proxy (also known as shared) servers.
- public
- Use this to mark a normally uncacheable object as cacheable. For example, an authenticated page is not normally cached (for security reasons). By setting this value you make sure it is indeed stored in the cache.
- no-cache
- This is used to force the object to be submitted to the original server to be validated before being released from cache. This is used when combined with "public" to ensure password protected pages are validated even if they are in cache.
- must-revalidate
- Orders the cache to obey your header rules.
- proxy-revalidate
- This is the same as "must-revalidate" except it applies only to proxy caches.
Content Ratings
The "content ratings" section allows you to inform browsers and other agents what kind of material your resources include. You can rate the resources based upon violence, sex, nudity and language.
Rating Service
The "rating service" tab allows you to set the ratings for the resource you specified.
To edit the ratings, click the "more info" button.
Setting ratings
is a very straightforward process. Select each of the four RSACi
categories and set the slider to the appropriate level. You have a choice
of 1-5 for each category.
It is best to be very honest when setting these values, as parents and filtering software will depend upon them to determine if your pages and resources are acceptable for their children's viewing. Incorrect settings will lose you visitors and sales.
You should also enter the email address of the person who performed the rating and set an expiration date as well.
MIME Map
Use the "MIME Map" tab to set custom MIME types for your resource.