Terry Donaldson wrote: > Darren > > Why so quick to throw out DNS? It seems to me that DNS has much more > accurate information and that can be obtained from local servers > rather than having to rely on an external server.
Well, to use the Microsoft example, find me all of the DNS nameserver (NS) records that serve Microsoft domain names. Include all of the country TLDs. Then make sure that the relevant NS's are able to provide you with names that can be found in every network address space assigned. In doing this you have to recognise that the registered names aren't likely to fully fill any particular CIDR address space, so you've no real surety about what is the first and last IP# assigned to the company. I'd contend that "from local servers" is also wrong. There's no guarantee that the answer to your DNS query will be either cached locally or in a server that you use for forwarding of queries. If you're not doing forwarding then obtaining a DNS answer involves talking to multiple remote servers on your behalf. For example, to find www.microsoft.com, you need to go to "." servers to find out who does "microsoft.com" and then go to the microsoft.com servers to find out what address www.microsoft.com is. The advantage DNS has is the lifetime of the data is better known and caching it is better understood. Darren
