DNS primer

[Roland Perry <[EMAIL PROTECTED]>]

In article <[EMAIL PROTECTED]>, Dave Howe <[EMAIL PROTECTED]> 
writes
> Roland Perry wrote:
> > In article <[EMAIL PROTECTED]>, Dave Howe 
> > <[EMAIL PROTECTED]>  writes
> > > the www is built on a disparate array of machines, managed by people of
> > > varying degrees of competence and usually held in systems maintained by
> > > external suppliers; DNS is simply an index into that system

DNS...

> > Indeed, and comparisons with a distributed database of *actual data* 
> > are  entirely fallacious :-(

> Are you suggesting there is no actual data on the internet at all? I 
> seem to find my ability to retrieve real, valuable and timely data from 
> the internet is very reliable indeed, and only rarely interrupted by 
> indexing problems or server unavailability.

The *DNS* is not a distributed database in what I'd claim to be the 
normal sense. It's a set of Mirrors of a number of stand-alone 
databases. OK, there exists software which will query the relevant 
individual stand-alone database, and that software is capable of 
accessing a Mirror if necessary; which kind of gives that impression.

But each Mirror has to be maintained (uploaded) {with a few modern 
exceptions} explicitly by the database owners. There's no automatic 
propagation of changes between the different mirrors, nor is there a 
scheme to force the early flushing of cached information where that 
exists in the channel between the database and the end user.

So the mechanisms in place to feed and water the DNS are entirely 
different to those that would need to be deployed to implement a truly 
distributed database of data that might be accessed by end users via 
http. Akamai would be a better system to look at.
--
Roland Perry