Date: Mon, 23 Jul 2007 11:04:16 +0700 (ICT) From: Olivier Nicole <on@cs.ait.ac.th> To: cswiger@mac.com Cc: freebsd-questions@freebsd.org, cuongvt@fpt.vn Subject: Re: is is able to setting up DNS server reverse lookup with DynamicIP? Message-ID: <200707230404.l6N44GhK053836@banyan.cs.ait.ac.th> In-Reply-To: <8928494B-76CC-4585-B95C-B4E5605F6DAF@mac.com> (message from Chuck Swiger on Mon, 16 Jul 2007 09:55:06 -0700) References: <46970917.3030502@fpt.vn> <200707130536.l6D5akxS070187@banyan.cs.ait.ac.th> <157815A5-2619-4457-85B0-40941C58C284@mac.com> <200707160607.l6G67tod005252@banyan.cs.ait.ac.th> <8928494B-76CC-4585-B95C-B4E5605F6DAF@mac.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi Chuck, With some delay, several answers together. > > For the example I gave, I am of course authoritative. > Are you? Depending on which servers I query, I either get an > NXDOMAIN, an answer with no authoritative nameservers listed, or the > results you've shown. That implies that there is something wrong > with the DNS delegation, and/or the various nameservers aren't > returning reliable results. I think that the no authoritative means it is an answer from a chache. Am I wrong? > Perhaps part of the problem seems to be that: > > % dig -t ns desktops.cs.ait.ac.th > ; <<>> DiG 9.3.4 <<>> -t ns desktops.cs.ait.ac.th > ;; global options: printcmd > ;; Got answer: > ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19501 > ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 > > ;; QUESTION SECTION: > ;desktops.cs.ait.ac.th. IN NS > > ;; ANSWER SECTION: > desktops.cs.ait.ac.th. 43049 IN NS dns.cs.ait.ac.th. > > ;; Query time: 1 msec > ;; SERVER: 127.0.0.1#53(127.0.0.1) > ;; WHEN: Mon Jul 16 12:48:42 2007 > ;; MSG SIZE rcvd: 57 > > ...doesn't return any A records to go with the NS record for > dns.cs.ait.ac.th. It's also the case that every domain should have > at least two nameservers listed, and by strong preference at least > one nameserver should be on another subnet to improve reliability. It should, because dns.cs.ait.ac.th has had a very stable IP for many years and this one is served by 3 name servers. When I set-up the dynamic DNS, I did not replicate it because I was not sure it woul dnot generate huge traffic, nor that redundancy was as needed as for the static DNS. But I am in the process of upgrading the hardware, so I will duplicate the name servers also for the dynamic part. > It's not anticipated that a reverse lookup would return a CNAME > rather than a PTR. CNAME in rDNS is to my knowledge the only way to delegate a subnet of a class C: I have a /24 IP range, /25 is static and /25 is dynamic. For separation, stability, etc, I want to rDNS on /25 and that is not possible without a trick: in the zone declaration for the rDNS of the /24 170.41.192.in-addr.arpa. I have a line that says: $GENERATE 128-254 $ IN CNAME $.170.41.192.rev-dns.cs.ait.ac.th. hence the CNAME and the PTR are generated dynamically in the zone 170.41.192.rev-dns.cs.ait.ac.th Best regards, Olivier
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200707230404.l6N44GhK053836>