Re: [Dnsmasq-discuss] using dnsmasq with 4 upstream servers
On Fri, Sep 02, 2016 at 01:23:44PM +0200, Daniel Steglich wrote: > I've got 4 upstream DNS Servers from my ISP (2 IPv4, 2 IPv6) and > use all of them in /etc/resolv.conf. I think you'd be better off to simplify this. Furthermore I am always leery of trusting ISP nameservers. Sooner or later the ISP bosses get the idea to increase revenue with NXDOMAIN redirection. Really, I'd trust Google before an ISP (but my own solution is to point dnsmasq at my own local caching resolver.) > I start sending DNS SRV querys from a client to dnsmasq DNS relay > every 5 seconds. > > Each request is sent to four DNS upstream servers (primary DNS v4, > secondary DNS v4, primary DNS v6, secondary DNS v6). The answer > from the fastest server is used. > As the requests are DNS SRV records, the reply is not cached by > dnsmasq. What? Why not? Caching is done based on TTL, not based on the RRtype. If the upstream server gives you a zero TTL, then that record is not cached ... regardless of RRtype. > During my tests the first IPv6 DNS server was always the fastest > replying server and for this reason the answer from this server > is passed to the client always, Do the answers from other upstream servers differ? > After some time the dnsmasq relay is not forwarding the requests to > the four known DNS servers any more but only sends out the requests > to either the first IPv4 DNS server or the first IPv6 DNS server. > So only one server is used. After about 20 seconds (4 requests > later) the dnsmasq process falls back to the expected behaviour of > sending the request to all known DNS Servers. I guess there is an implied "but the server fails to answer" in this, and it presents yet another reason why you might want to consider these ISP nameservers unreliable. > does anybody knows the reason for this? See --all-servers and --server in the manual. -- http://rob0.nodns4.us/ Offlist GMX mail is seen only if "/dev/rob0" is in the Subject: ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
[Dnsmasq-discuss] using dnsmasq with 4 upstream servers
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Hi, I've got 4 upstream DNS Servers from my ISP (2 IPv4, 2 IPv6) and use all of them in /etc/resolv.conf. I start sending DNS SRV querys from a client to dnsmasq DNS relay every 5 seconds. Each request is sent to four DNS upstream servers (primary DNS v4, secondary DNS v4, primary DNS v6, secondary DNS v6). The answer from the fastest server is used. As the requests are DNS SRV records, the reply is not cached by dnsmasq. During my tests the first IPv6 DNS server was always the fastest replying server and for this reason the answer from this server is passed to the client always, After some time the dnsmasq relay is not forwarding the requests to the four known DNS servers any more but only sends out the requests to either the first IPv4 DNS server or the first IPv6 DNS server. So only one server is used. After about 20 seconds (4 requests later) the dnsmasq process falls back to the expected behaviour of sending the request to all known DNS Servers. does anybody knows the reason for this? - --- Mit freundlichen Grüßen Daniel Steglich -BEGIN PGP SIGNATURE- Version: Mailvelope v1.5.1 Comment: https://www.mailvelope.com wsFcBAEBCAAQBQJXyWDvCRCe/ByBcnU4rwAABSoP/2EaTSwE2ZMc5uUUbmxJ qv7cGtTEaPfddGmA0ua0/kUJRw47w3VHzChxIjWF9L9DmQf5q3rXzD8i5Cfu E+1UURKAJ1YLgztzz2GBAclZ0lUA+HNIk8VgIxicbyeS+9HP35dwFFfm90D9 j/DBfIiRq9/VI+EdWwHEnZ3KLpvyS3Wqd7z039VB/GoPo7J6lDJmD7vCJmQU tAxfVB/XTfxaskiMBd/Eeg//Tdesofnwcp5YEbHsl/aR6NHH/73I5f8VlTP0 gEzQ/kd8+2qCBFzi/C4VhTmm4hxdY7RlSsmefqK3YOMeSs+l8zNL5p+igry5 wPjRN03Hnfqcpyy7MpKPiX8faP5xRCrXQgW+DDt+koDdAKauDiAryemM0Rxu pzQ7QVpZAF0O76QJrW5XofuP+53JktAY61IV7W2/J5EAbouZfmUJ27N4mBH5 gLUWrEARpDDcYtYNrU4GP4u6hPEjx6AMnrMc0TqCmukkPKCigZulAkL9lXHw DsdeznI/l/i7SyVikVMny6G2PBGi/5OX9KFUaWvszMEKqOiyaOI7CyEjLaiA 02ShtvIDamArhZOjKljEr+2ws0JA7WZ6w81ItqyTQvoXJQ5xxRXHxzLlM8v6 R6Gex8Wtz+uqbMmR3/VAZXcxF5QgloaOLUfejVKo9R6lAbxJYiIVwKVLjTMt 2hHi =mpBi -END PGP SIGNATURE- ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
