This is a discussion on Re: 'dig -t any ...' question within the Bind Users forums, part of the DNS and Related Forums category; >>>>> "Ladislav" == Ladislav Vobr <lvobr@ies.etisalat.ae> writes: Ladislav> what'...
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>>>>> "Ladislav" == Ladislav Vobr <lvobr@ies.etisalat.ae> writes:
Ladislav> what's so special about ANY? Nothing. You just don't seem to understand what it means. A QYTPE of ANY means "give me whatever RRs you have for this name". That's all. See my earlier posting for more info. Ladislav> Why any recursive servers don't do it's best to satisfy Ladislav> the recursive client with the reply from the authoritative Ladislav> server, that's why we call it recursive right? Wrong. We call it recursive because the server is able to recursively make iterative queries to resolve a query on behalf of some client. It doesn't mean the server does that: it can answer from its cache which might or might not have been populated with data returned from earlier queries to authoritative servers. No assumptions can or should be made about how a recursive server provides answers. It should of course interrogate authoritative servers when nothing has been cached. But that cannot be guaranteed. And even if it does query authoritative servers, the answer might not be correct. The DNS is loosely coupled remember. It can take time for a zone's authoritative servers to converge on the same copy of the zone data after the zone gets updated. They don't all update the zone simultaneously. You seem to think that an ANY QTYPE means a server must retrieve every RR for the name. That's not the case. In fact this is impossible. The master server could change the RRs immediately after answering your hypothetical EVERY query before that reply gets back to the client. It's not even the case that a server must query an authoritative server in order to respond to an ANY query. Remember too that one of the key strengths of the DNS is caching. In some sense this means that recursive servers are lazy. They'll answer from cache every time unless there's nothing relevant in the cache and they're forced to resolve something. This is why people need to think carefully about TTL values. How many times have we seen postings here where there's been a long-lived TTL for a web or mail server that then gets renumbered and the poster whines that traffic still goes to the old address even though they've updated the zone? Ladislav> to do this kind of work for the Ladislav> client, how can it take answer from the parent and Ladislav> consider the task done? Because that's how the DNS works. Ladislav> I have problem with ladislav.name.ae .... snipped .... This appears to be either a wierd local set-up or else you have a misunderstanding of what's going on. |
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