Re: Re send-n for query optimisation

Lawrence Conroy said:
>  As Paul pointed out, this is not a UK-only problem.
> However, looking at your numbers, I think you are gilding the lilly.
> I disagree with your figures for the generality of UK telephone users.
> 
> I would have used: 6 calls per day, 3-4 in busy two hour period.
> Average call length << 1 hour.

Average call length of 3 minutes is, I believe, the standard used in UK
telephony planning.

I can't remember where I got the "1 hour usage per day" figure from, so I
can't help with that. But my phone bill typically has at least 6 chargeable
calls per day, and this excludes all off-peak calls to landlines in the UK
(which are free on the package I'm subscribed to).

> As for call attempts / completed calls, I'd defer to Paul if he's
> willing to give out some numbers for his network. 4 call attempts
> per completed call seems high.

You misread; I'm suggesting 1.25 attempts per completed call (that is, one
failure for every 4 successful calls).

> The total number of queries is distributed over the whole of the UK.
> You are thinking about a decentralized system, I hope? This is DNS.

Yes, but the question is how many calls can be served off the caches and
how many go back to the authoritative server.

Plus it's not just the DNS. The switches have to make the queries and this
takes CPU away from other tasks. Reducing the load on the switches is part
of the objective.

> It also does cacheing. The propensity of people to call any individual
> number is low, but not always. Particularly with the "problem" ones in
> the UK, the propensity is likely to be much higher. For example, if we
> are to believe the Daily Mail and its ilk,

Don't go there. Please.

> there must be thousand upon
> thousand of calls to 0800 1111. This is going to remain resident in the
> cache of any provider's full-service resolver.

True. But that doesn't help with other numbers.

> So - assuming a distributed system with separate authoritative servers
> and full-service resolvers, does it really matter whether or not one
> saves 50% or 75% of queries?

I would have still thought so, yes.

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