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Re: Alternative to BGP-4 for multihoming?
On Tue, 14 Mar 2000, Pete Templin wrote: > On Tue, 14 Mar 2000, Marc Slemko wrote: > > > Saying "the clients's primary DNS" is misleading. There is no way to know > > what the "primary" DNS server is for a zone, and there may not even be > > what is typically known as a primary. > > What if it's a UUNet resold modem to a client of iAmerica - what server > gets used then? We know that UUNet's DNS servers are likely to not be > located close (in net terms) to the client, and how do we know what DNS > servers are being assigned to the client? > User's machine contacts caching nameserver x to do a lookup. Nameserver x contacts authoritative nameserver y, which then works out where x is before returning an RR that's good for wherever x is. If n isn't net.near to the user's machine, then something's a bit weird. If part of a dialup ISP's internal network falls over, you hardly want every single user's resolvers to fail! > Or what if my clients get assigned dns servers in 192.168.254/24? Sounds > to me like it's not a valid geographic identifier. > I'd hope that nameserver would talk to the world with a real source address, which y would then use to do a proximity test, rather than a 1918 address - at least it should if it actually wants to get a response. What address the client-side interface uses is neither here nor there. -- Patrick Evans - Sysadmin, bran addict and couch potato pre at pre dot org www.pre.org/pre