In article <mailman.1499.1296009856.555.bind-us...@lists.isc.org>, p...@mail.nsbeta.info wrote:
> I'm reading the document "Secure DNS Deployment Guide" got from the URL a > poster gave in the list. > > The document said: > > When a user types the URL www.example.com into a Web browser, the browser > program contacts a type of resolver called a stub resolver that then > contacts a local name server (called a recursive name server or resolving > name server). The resolving name server will check its cache to determine > whether it has valid information (the information is determined to be valid > on the basis of criteria described later in this document) to provide IP > address for the accessed Internet resource > (i.e.,www.marketing.example.com). If not, the resolving name server checks > the cache to determine whether it has the information regarding the name > server for the zone marketing.example.com (since this is the zone that is > expected to contain the resource www.marketing.example.com). If the name > server!Ës IP address is in the cache, the resolver!Ës ne query will be > directed against that name server. If the IP address of the name server of > marketing.example.com is not available in the cache, the resolver > determines whether it has the name server information for a zone that is > one level higher than marketing.example.com (i.e., example.com). If the > name server information for example.com is not available, the next search > will be for the name server of the .com zone in the cache. > > > I think the statement below is wrong? > > > If not, the resolving name server checks the cache to determine whether it > > > has the information regarding the name server for the zone > > marketing.example.com (since this is the zone that is expected to contain > > > the resource www.marketing.example.com). > > > How does the resolver know www.marketing.example.com is a domain name or a > zone? www.marketing.example.com can also be a zone which has valid NS > records. So I was thinking the resolver shall check the cache firstly to > see whether it has the NS records for the zone www.marketing.example.com, > if not, then to check the NS for marketing.example.com. Am I right? > > Regards. You're correct. -- Barry Margolin, bar...@alum.mit.edu Arlington, MA *** PLEASE don't copy me on replies, I'll read them in the group ***
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