To update, we can use the following mechanisms:

• Have clients maintain multiple FSAs (one large, compressed one and a smaller, uncompressed but easy-to-update one). Occasionally (much less frequently than the standard update interval), merge the smaller FSA into the larger FSA and have the client download the new full FSA.
• Send a compressed list of added and removed domain names to the client, and have the client uncompact and update the FSA locally.
• Determine an efficient way for representing updates to the compacted FSA and send these to the client. Currently, the thought is that these could change drastically due to changing of Huffman encodings. It's unclear how changes in the FSA will propagate through the compacted form.