Re: DNS queries go to primary and secondary DNS servers at the same time
OK, thanks a lot for your comments. I'll investigate this topic. Greetings !!! El mar., 17 dic. 2019 a las 14:42, Chuck Aurora () escribió: > On 2019-12-16 13:13, Roberto Carna wrote: > > I have a primary and a secondary BIND9 DNS servers, working as master > > / slave with zone transfers between them. > > Primary/master and secondary/slave are concepts which apply only to > authoritative servers, and in this case you are talking about these > servers acting as resolvers, not authoritative. > > > I have several Linux machines (desktops and servers) with Debian and > > Mint. > > > > I've realized, using TCPDUMP at DNS1 and DNS2, that all DNS queries > > from Linux machines go to both DNS1 and DNS2 BIND servers at the same > > time. > > > > In all Linux machines we have setup the DNS resolution using > > /etc/resolv.conf: > > And resolv.conf is not an ISC BIND thing. In GNU/Linux it's usually > GNU glibc which uses that file. > > > nameserver IP_dns1 > > nameserver IP_dns2 > > > > But when the from Linux clients I execute: > > > > $ host > > > > I can see UDP traffic arriving to DNS1 and DNS2 at the same time. > > > > What can be the problem ? > > I'm not sure I would see that as a problem, although you might want to > simplify and use only a single resolver IP address. If your site is > big enough to need two or more resolvers, use an anycast address. For > example, Google's 8.8.8.8 is a large farm of nameservers distributed > throughout the world. > > > Because I expect only DNS traffic going to > > DNS1 because it is before DNS2 in /etc/resolv.conf. > > GNU glibc does have documentation, starting with the resolv.conf(5) > manual. I'm not sure if there is a specific mailing list or forum to > discuss it, however. > ___ > Please visit https://lists.isc.org/mailman/listinfo/bind-users to > unsubscribe from this list > > bind-users mailing list > bind-users@lists.isc.org > https://lists.isc.org/mailman/listinfo/bind-users > ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
Re: DNS queries go to primary and secondary DNS servers at the same time
On 2019-12-16 13:13, Roberto Carna wrote: I have a primary and a secondary BIND9 DNS servers, working as master / slave with zone transfers between them. Primary/master and secondary/slave are concepts which apply only to authoritative servers, and in this case you are talking about these servers acting as resolvers, not authoritative. I have several Linux machines (desktops and servers) with Debian and Mint. I've realized, using TCPDUMP at DNS1 and DNS2, that all DNS queries from Linux machines go to both DNS1 and DNS2 BIND servers at the same time. In all Linux machines we have setup the DNS resolution using /etc/resolv.conf: And resolv.conf is not an ISC BIND thing. In GNU/Linux it's usually GNU glibc which uses that file. nameserver IP_dns1 nameserver IP_dns2 But when the from Linux clients I execute: $ host I can see UDP traffic arriving to DNS1 and DNS2 at the same time. What can be the problem ? I'm not sure I would see that as a problem, although you might want to simplify and use only a single resolver IP address. If your site is big enough to need two or more resolvers, use an anycast address. For example, Google's 8.8.8.8 is a large farm of nameservers distributed throughout the world. Because I expect only DNS traffic going to DNS1 because it is before DNS2 in /etc/resolv.conf. GNU glibc does have documentation, starting with the resolv.conf(5) manual. I'm not sure if there is a specific mailing list or forum to discuss it, however. ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
Re: DNS queries go to primary and secondary DNS servers at the same time
Am 16.12.19 um 20:13 schrieb Roberto Carna: > I have a primary and a secondary BIND9 DNS servers, working as master / > slave with zone transfers between them. > > I have several Linux machines (desktops and servers) with Debian and Mint. > > I've realized, using TCPDUMP at DNS1 and DNS2, that all DNS queries from > Linux machines go to both DNS1 and DNS2 BIND servers at the same time. > > In all Linux machines we have setup the DNS resolution using > /etc/resolv.conf: > > nameserver IP_dns1 > nameserver IP_dns2 > > But when the from Linux clients I execute: > > $ host > > I can see UDP traffic arriving to DNS1 and DNS2 at the same time. > > What can be the problem ? Because I expect only DNS traffic going to > DNS1 because it is before DNS2 in /etc/resolv.conf it's not unusual behavior these days that a client asks both nameservers and takes the answer of the faster one that avoid large delays in case of timeouts when the asked one is down ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
Re: DNS queries go to primary and secondary DNS servers at the same time
On 16.12.19 16:13, Roberto Carna wrote: I have a primary and a secondary BIND9 DNS servers, working as master / slave with zone transfers between them. I have several Linux machines (desktops and servers) with Debian and Mint. I've realized, using TCPDUMP at DNS1 and DNS2, that all DNS queries from Linux machines go to both DNS1 and DNS2 BIND servers at the same time. In all Linux machines we have setup the DNS resolution using /etc/resolv.conf: nameserver IP_dns1 nameserver IP_dns2 But when the from Linux clients I execute: $ host I can see UDP traffic arriving to DNS1 and DNS2 at the same time. maybe modified version of the "host" command? What can be the problem ? Because I expect only DNS traffic going to DNS1 because it is before DNS2 in /etc/resolv.conf. -- Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. Linux is like a teepee: no Windows, no Gates and an apache inside... ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
Re: DNS queries go to primary and secondary DNS servers at the same time
I add something interesting: If I execute the same query with dig: $ dig The query traffic goes only tu DNS1 and not to DNS2. Maybe a host command problem ??? Thanks again !!! El lun., 16 dic. 2019 a las 16:13, Roberto Carna () escribió: > Hi people, > > I have a primary and a secondary BIND9 DNS servers, working as master / > slave with zone transfers between them. > > I have several Linux machines (desktops and servers) with Debian and Mint. > > I've realized, using TCPDUMP at DNS1 and DNS2, that all DNS queries from > Linux machines go to both DNS1 and DNS2 BIND servers at the same time. > > In all Linux machines we have setup the DNS resolution using > /etc/resolv.conf: > > nameserver IP_dns1 > nameserver IP_dns2 > > But when the from Linux clients I execute: > > $ host > > I can see UDP traffic arriving to DNS1 and DNS2 at the same time. > > What can be the problem ? Because I expect only DNS traffic going to DNS1 > because it is before DNS2 in /etc/resolv.conf. > > Thanks a lot !!! > ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
DNS queries go to primary and secondary DNS servers at the same time
Hi people, I have a primary and a secondary BIND9 DNS servers, working as master / slave with zone transfers between them. I have several Linux machines (desktops and servers) with Debian and Mint. I've realized, using TCPDUMP at DNS1 and DNS2, that all DNS queries from Linux machines go to both DNS1 and DNS2 BIND servers at the same time. In all Linux machines we have setup the DNS resolution using /etc/resolv.conf: nameserver IP_dns1 nameserver IP_dns2 But when the from Linux clients I execute: $ host I can see UDP traffic arriving to DNS1 and DNS2 at the same time. What can be the problem ? Because I expect only DNS traffic going to DNS1 because it is before DNS2 in /etc/resolv.conf. Thanks a lot !!! ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
