On Sat, 2008-08-09 at 07:43 +0000, MontyRee wrote: > Hello, all. > > > I have operated two dns(primary and secondary) for one domain like below. > > > example.com IN NS ns1.example.com > example.com IN NS ns2.example.com > > > and there was a event that ns1.example.com dns was down. > As I know, if ns1 dns is down, all requests go to the ns2.example.com.
Depending on what "down" means, it could take some time before the request is sent to ns2. So there will likely be a delay, even if not much (it will feel like forever to some users). > > But when ns1.example.com dns was down, actually some people can't lookup the > domain. Sounds like a configuration issue. However realize there is a zone cache and if ns2 is slaving zones of ns2 (typical bind master slave scenario) and the zone cache expires, then ns2 will refuse to trust the slaved zone it had... and thus nothing works. > > What's the problem and how can I solve this problem? > > If I adding some dns server like ns3,ns4.ns5, it would be helpful to solve > this problem? No if it's the cache issue... but that's if we're talking about authoritative zones that you're serving. If you're just needing some nameservers that answer recursively for generic requests and many are of dubious quality, then adding extra "might" help.... but I'd suspect something else is wrong before I'd do that.
