It is dependent upon the browser and server, however in RFC 2068 it states
Servers should be cautious about depending on URI lengths
above 255 bytes, because some older client or proxy
implementations may not properly support these lengths.
Since the GET method packs all it's information into the URI, yo shouldn't work with a URI (that is internet address plus data) of > 255 bytes.
Read the RFC (Request for Comment). It's dry, but has a lot of info in it and helps you learn the history of the Internet. The RFCs are a compilation of all the documents and communications which helped set the standards and lay the foundation for the internet. They also contain information on upcoming standards.
