equivalent HTTP queries get different responses

Question

GET http://d9.c4.b1.a0.top.list.ru/ HTTP/1.0\r\nHost: d9.c4.b1.a0.top.list.ru\r\n\r\n

response:

HTTP/1.0 400 Bad Request
Server: wz/1.5
Date: Sat, 17 Nov 2012 19:00:20 GMT
Cache-control: no-store, no-cache, must-revalidate
Pragma: no-cache
Content-Length: 0
Connection: close

---

GET / HTTP/1.0\r\nHost: d9.c4.b1.a0.top.list.ru\r\n\r\n

response:

HTTP/1.0 302 Moved Temporarily
Server: wz/1.5
Date: Sat, 17 Nov 2012 19:06:27 GMT
Location: http://top.mail.ru/
Cache-control: no-store, no-cache, must-revalidate
Pragma: no-cache
Content-Length: 0
Connection: close

What is difference between these queries?

P.S. Queries were made using telnet.

Answer 1

From the HTTP 1.0 specification on the Request-URI:

The absoluteURI form is only allowed when the request is being made to a proxy.

So it seems that the server you send this request to is not a proxy but probably the specified server itself.

Using the absolute URI in the request line in a request sent to the specified server is only valid in HTTP 1.1:

To allow for transition to absoluteURIs in all requests in future versions of HTTP, all HTTP/1.1 servers MUST accept the absoluteURI form in requests, even though HTTP/1.1 clients will only generate them in requests to proxies.