On 3/13/07, Nathan Ward
That's not uncommon these days. Things like Foundry GSLB (Global Server Load Balancing) and Cisco DistributedDirector sit in front of DNS servers (or are DNS servers in some cases), and return records with low (or zero) TTLs. This is configurable with Foundry (default 10s), I'm not sure about Cisco and others.
I believe TradeMe have some Foundry kit, so it's not inconceivable that they have GSLB turned on.
I did read somewhere recently that zero-second TTLs have a bad effect on some clients resolvers, something like they instead use their 'default' which is 15 minutes in many cases. Google doesn't love me today though, so I can't give you references to it.
DNS looks like a nice thing to use in DR or load balancing situations, however, in most cases it just doesn't work. I've seen a lot of ISPs that cache all DNS entries, no matter what the TTL value says. Using a TTL of 10 seconds, like what Trademe has, doesn't guarantee that, if you change the IP address, it will take only 10 seconds for clients. For example, Internet Explorer will cache the DNS entry for 30 minutes, no matter what was in the TTL (previous versions, <3.0 cached it for 24 hours!). You can change this with a registry key but I doubt anyone does that. Bojan