Which header indicates the compression encoding used for an HTTP response?

• A. Content-Encoding
• B. Transfer-Encoding
• C. Content-Type
• D. Content-Length

Answer: (D)

When a server compresses the response body, it communicates the method used to the client so the recipient can decompress it correctly. That information is carried in the header that specifies the encoding of the payload, such as gzip, br, or deflate. This header is present in the HTTP response and directly tells the client how to interpret the compressed data.

Transfer-Encoding is about how the message itself is carried over the network (for example, chunked transfer), which can be related to transmission but does not describe the compression method applied to the body. Content-Type indicates what kind of data the body contains (like text/html or application/json). Content-Length tells you how many bytes are in the body, but not how that body is encoded.

So the header that indicates the compression encoding used for an HTTP response is Content-Encoding.