Re: [DNSOP] Please review the definitions around "recursive" in terminology-bis

P Vix <> Mon, 12 March 2018 17:21 UTC

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Date: Mon, 12 Mar 2018 17:21:48 +0000
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From: P Vix <>
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Subject: Re: [DNSOP] Please review the definitions around "recursive" in terminology-bis
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No cc. I call them full resolved not recursive resolvers. I thought 1034 also did.

On March 12, 2018 3:09:27 PM UTC, Paul Hoffman <> wrote:
>Greetings. The definition of "recursive resolver" has been problematic 
>both in RFC 7719 and in draft-ietf-dnsop-terminology-bis. Section 6 of 
>draft-ietf-dnsop-terminology-bis defines a bunch of terms about
>including "recursive mode" and "recursive resolver". The current text 
>    Recursive mode:  A resolution mode of a server that receives DNS
>       queries and either responds to those queries from a local cache 
>       sends queries to other servers in order to get the final answers
>      to the original queries.  Section 2.3 of [RFC1034] describes this
>       as "The first server pursues the query for the client at another
>       server".  A server operating in recursive mode may be thought of
>       as having a name server side (which is what answers the query) 
>       a resolver side (which performs the resolution function).  
>       operating in this mode are commonly called "recursive servers".
>       Sometimes they are called "recursive resolvers".  While strictly
>      the difference between these is that one of them sends queries to
>       another recursive server and the other does not, in practice it 
>       not possible to know in advance whether the server that one is
>       querying will also perform recursion; both terms can be observed
>       in use interchangeably.
>    Recursive resolver:  A resolver that acts in recursive mode.  In
>      general, a recursive resolver is expected to cache the answers it
>       receives (which would make it a full-service resolver), but some
>       recursive resolvers might not cache.
>That is, "recursive mode" is only barely defined in RFC 1034, and 
>"recursive resolver" is defined almost trivially.
>Can these be improved on? This is one of the core ideas in the DNS 
>protocol and it seems a bit weird that we don't have a crisp set of 
>definitions. If there is more text from RFCs to quote, that would 
>possibly be a big help.
>--Paul Hoffman
>DNSOP mailing list

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