In message <[EMAIL PROTECTED]>, Zhang Bao Feng writ
es:
>Dear Eastlake,
>
>You are absoutly right, but if considering about the end-to-end SIP call, this
> lookup time will make some influence with the calling establish time, as Mich
>ael mentioned, "The performance of lookups scales linearly (worst case) with
> the number of zone cuts ".
>
>So that's the reason why I want to know the real-data about the lookup time in
> current DNS system. :-) It may be a problem for real-time applications.
>
I believe that the crucial factor is whether or not the relevant
NS records and their associated A records are cached. If they are,
lookups will go very quickly. Of course, the cache is populated by the
first such lookup, so that one might be somewhat slower.
--Steve Bellovin, http://www.research.att.com/~smb
