Stop using low DNS TTLs
The irony of all of this is that those TTLs are almost meaningless as a server operator anyway.  Even if you set your TTL to 5 minutes, there are a whole lot of clients that will ignore it.<p>When I made a DNS switch at reddit, even with a 5 minute TTL, it still took an hour for 80% of the traffic to shift.  After a week, only 95% had shifted.  After two weeks we still had 1% of traffic going to the old IP.<p>And after a month there was still some traffic at the old endpoint.  At some point I just shut off the old endpoint with active traffic (mostly scrapers with hard coded IPs at that point as far as I could tell).<p>One of my friends who ran an ISP in Alaska told me that they would ignore all TTLs and set them all to 7 days because they didn't have enough bandwidth to make all the DNS queries to the lower 48.<p>So yeah, set your TTL to 40 hours.  It won't matter anyway.  In an emergency, you'll need something other than DNS to rapidly shift your traffic (like a routed IP where you can change the router configs).