On 22 September 2014 12:27, Tony Finch <d...@dotat.at> wrote: > Dick Franks <rwfra...@acm.org> wrote: > > On 22 September 2014 11:03, Tony Finch <d...@dotat.at> wrote: > > > > > > (1) Master-only. The master observes an ANAME record at the apex of a > zone > > > it loads and uses it to periodically refresh the relevant records in > the > > > zone (as if you had a cron job running dig | magic | nsupdate). > > > > > > Disadvantage: potentially lots of XFR traffic if the TTLs are low. > > > > Why would TTL be relevant here? > > > > Is the master not acting as a "partial slave" for the target RRs? > > In which case, the timing should depend on the SOA refresh period. > > Yes, you could do it that way. But a lot of people want changes to take > effect quickly. > > So whenever TTL times out, master does validated lookup of each ANAME target, resigns, updates zone, notifies own slaves, services XFRs.
Someone beyond your direct control sets a short TTL (0 or 1) in ANAME target RRs and your master is in deep, deep [trouble] !! Thinking about it, (target side) SOA refresh is not much better. > And I forgot to cover the effects that client-subnet might have ... > > I do not know either Rs Dick
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