I've checked about a dozen of web sites and I've noticed that most of them use a low TTL value in their SOA record.
Usually it's up to 1 hour. I set for my site 1 week (604800 sec.) .
So my question is... why for normal operation do sites set such low TTL values? What's the advantage? I can only see disadvantages here. More traffic, latency, more load on the servers. But maybe I'm wrong... Maybe there's something I don't know about the issue?