On 4-jun-2007, at 4:33, Stephen Satchell wrote:

The last time I renumbered, I found that quite a few people were not honoring the TTLs I put in my DNS zone files. I would clone the new address and monitor traffic to the old address -- and it took up to seven days for the traffic to the old address to die down enough that I could take it out.

Are you sure this was the result of DNS servers increasing the TTL, not simply applications doing their own caching?