(I am not an expert on this, so may be wrong, but...) How does that change anything?
If the client needs to know foo.example.com they ask the nearest server. That will have the wildcard and will return the correct address. The nearest server is not going to be the root server for that domain, but something (typically) at the ISP. So the ISP DNS server will see more load, but not the root. Yet this article show the root as getting a huge number of hits. The only explanation I see is that they are not serving wildcard responses when they should be...
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ok i'm confused. why doesn't dns wildcard caching solve this?
DNS wildcards are server-side, so there's no way for the client to know that the response they got is for *.domain.com but not www.domain.com.
(I am not an expert on this, so may be wrong, but...) How does that change anything?
If the client needs to know foo.example.com they ask the nearest server. That will have the wildcard and will return the correct address. The nearest server is not going to be the root server for that domain, but something (typically) at the ISP. So the ISP DNS server will see more load, but not the root. Yet this article show the root as getting a huge number of hits. The only explanation I see is that they are not serving wildcard responses when they should be...