Re: [CentOS] /etc/resolv.conf - Number of Nameservers
On Sun, 2008-03-09 at 22:02 -0700, John R Pierce wrote: Manish Kathuria wrote: What is the maximum number of nameservers mentioned in /etc/resolv.conf which will be queried while looking up a hostname or IP address in the present version ? Earlier implementations had a ceiling of 3 name servers which could be queried. Has there been any increase ? only one server is ever queried. only if it if it can't be reached at all will it fall back on the 2nd one (and if that can't be reached, the 3rd) a answer of 'host not found' from the primary server does /not/ trigger any fallback, instead it returns not found. so, why would you need more than 3 ? DNS servers should have a . uptime. The idea is to switch between multiple internet links for the same internal network, without making frequent changes to /etc/resolv.conf. The ISPs here don't allow DNS look ups from an IP not belong to their address, so a number of look up requests get denied when the outgoing connection is through another ISP. Of course, I can run a caching nameserver on the small network or use Open DNS servers but that adds to the delay. Thank you, Manish ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] /etc/resolv.conf - Number of Nameservers
Manish Kathuria wrote: The idea is to switch between multiple internet links for the same internal network, without making frequent changes to /etc/resolv.conf. The ISPs here don't allow DNS look ups from an IP not belong to their address, so a number of look up requests get denied when the outgoing connection is through another ISP. Of course, I can run a caching nameserver on the small network or use Open DNS servers but that adds to the delay. not half as bad as having every lookup try and go to the first server in /etc/resolv.conf, then fail, and try the 2nd, repeating until one resolves. sounds like you should be running a caching name server, maybe even something thats aware of your ISP multiplexing scheme so it can dynmically choose forwarders a local caching name server shouldn't add any significant delay, and will greatly speed up frequent lookups. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
[CentOS] /etc/resolv.conf - Number of Nameservers
What is the maximum number of nameservers mentioned in /etc/resolv.conf which will be queried while looking up a hostname or IP address in the present version ? Earlier implementations had a ceiling of 3 name servers which could be queried. Has there been any increase ? Thanks, Manish ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] /etc/resolv.conf - Number of Nameservers
Manish Kathuria wrote: What is the maximum number of nameservers mentioned in /etc/resolv.conf which will be queried while looking up a hostname or IP address in the present version ? Earlier implementations had a ceiling of 3 name servers which could be queried. Has there been any increase ? only one server is ever queried. only if it if it can't be reached at all will it fall back on the 2nd one (and if that can't be reached, the 3rd) a answer of 'host not found' from the primary server does /not/ trigger any fallback, instead it returns not found. so, why would you need more than 3 ? DNS servers should have a . uptime. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
