How can I increase the TTL for the cached entries in my local dns serveder?

[Hongyi Zhao]

Hi all,

Currently, I use bind9 as the local dns cache server and a forwarder only
server.

I set the dnscrpyt-proxy running on local port 50 as the upstream dns
server  for my bind9 dns cache server.

In addtition, I also want to have long TTL so that I can obtain a short
inquiry respond time.

For all of the above purposes, I use the following configure file:

-------------------
$ cat /etc/bind/named.conf.options
options {
    directory "/var/cache/bind";

    // If there is a firewall between you and nameservers you want
    // to talk to, you may need to fix the firewall to allow multiple
    // ports to talk.  See http://www.kb.cert.org/vuls/id/800113

    // If your ISP provided one or more IP addresses for stable
    // nameservers, you probably want to use them as forwarders.
    // Uncomment the following block, and insert the addresses replacing
    // the all-0's placeholder.

    // forwarders {
    //     0.0.0.0;
    // };

        forward only;
        forwarders {127.0.0.1 port 50 ;} ;

        cleaning-interval 1440;
    max-cache-ttl 2419200;
    max-ncache-ttl 86400;
    max-cache-size unlimited;
    stacksize unlimited;
    datasize unlimited;
    coresize unlimited;


//========================================================================
    // If BIND logs error messages about the root key being expired,
    // you will need to update your keys.  See https://www.isc.org/bind-keys

//========================================================================
//    dnssec-validation auto;

    auth-nxdomain no;    # conform to RFC1035
    listen-on-v6 { any; };
};
-----------------------

Then I restart my dns server with the followoing command to let the above
config take in effect:

sudo service bind9 restart

But, I still have low TTL, because I've tried that the following command:

----------------
werner at debian:~$ dig ssh.sshcenter.info

; <<>> DiG 9.8.4-rpz2+rl005.12-P1 <<>> ssh.sshcenter.info
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 676
;; flags: qr rd ra; QUERY: 1, ANSWER: 15, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;ssh.sshcenter.info.        IN    A

;; ANSWER SECTION:
ssh.sshcenter.info.    60    IN    CNAME    c-ssh.cloudkvm.net.
c-ssh.cloudkvm.net.    60    IN    A    23.226.226.124
c-ssh.cloudkvm.net.    60    IN    A    69.197.147.93
c-ssh.cloudkvm.net.    60    IN    A    96.44.134.231
c-ssh.cloudkvm.net.    60    IN    A    107.150.4.170
c-ssh.cloudkvm.net.    60    IN    A    162.211.227.83
c-ssh.cloudkvm.net.    60    IN    A    173.254.237.179
c-ssh.cloudkvm.net.    60    IN    A    192.3.23.197
c-ssh.cloudkvm.net.    60    IN    A    192.161.175.143
c-ssh.cloudkvm.net.    60    IN    A    192.227.161.20
c-ssh.cloudkvm.net.    60    IN    A    199.119.224.224
c-ssh.cloudkvm.net.    60    IN    A    199.233.236.200
c-ssh.cloudkvm.net.    60    IN    A    23.90.4.124
c-ssh.cloudkvm.net.    60    IN    A    23.92.50.22
c-ssh.cloudkvm.net.    60    IN    A    23.94.104.29

;; Query time: 1208 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Mar 28 14:04:01 2014
;; MSG SIZE  rcvd: 292
--------------------

Though in above query, the query time is 1208 msec, if I immediately do the
second query, the query time will be dramtically shorttened.  But after
several minites, I will still obtain a long  query time as the above one.
The OS used by me is Debian GNU/Linux 7.4 (wheezy).

Any hints on this issue?

Regards
-- 
Hongyi Zhao <hongyi.zhao at gmail.com>
Xinjiang Technical Institute of Physics and Chemistry
Chinese Academy of Sciences
GnuPG DSA: 0xD108493
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