bugs: Web servers

This is a list of bugs and cache-unfriendly behaviours by Web servers. Hopefully, vendors will fix these problems; I don't intend to point fingers, but rather to help point out problems. It isn't complete; please send me any more that you find.

You can also see a similar listing for Proxy/Caches.

Apache

mod_expires erases any Cache-Control headers set. If you use the mod_expires directives to set an expiry time, it will overwrite any CC headers set (at any time); this makes it impossible, for instance, to set Cache-Control: public. [report]
mod_autoindex does not set Cache-friendly headers - including Content-Length (so that it can't be in a persistent connection) and Last-Modified (so it can't be validated). [report]

Netscape Enterprise Server

HEAD does not always return the same headers as GET. This is an unfriendly behaviour to caches as well as many robots. Particularly, Last-Modified is not returned when making a HEAD request for a default document (i.e., http://www.foo.com/bar/). [reported to Netscape]

Microsoft IIS

IIS 3.0 requires an Accept header when it shouldn't. Under some circumstances, IIS 3.0 will require that requests have an Accept header, even though it advertises itself as a HTTP/1.0 server. This happens most often for images.

NSCA HTTPd

HTTP/1.1 requests are responded to with an illegal Status line. For instance, if you send "GET / HTTP/1.0" to this server, it will respond with a status line such as "HTTP/1.0 200 Document Follows". However, if you give it "GET / HTTP/1.1", the response is "HTTP 200 Document Follows" (note the lack of a protocol version), which is unparseable.

StarNine WebSTAR

Date headers are served erratically - sometimes Date headers are skewed (usually between 5 and 10 minutes), and on other responses, a Date header is not send at all. This behaviour can be seen on the same object, from the same server instance, and varies each time the object is requested.
LM/IMS Validation does not work - even though WebSTAR serves Last-Modified headers for static content, it does not reply to conditional requests with 304 Not Modified; instead, it re-serves the same object in a 200 OK response.

Lotus Domino

Too many to list.