I have set up an 'internal' DNS at my work, basically we have ourdomain.com that is for internet, email etc and I have created on one of our linux network servers (debian) a DNS using bind9 with the domain ourdomain.inc.

So based on my files below and the symptoms I'm describing; what effect could IPV6 be having on my setup? What can I do to fix this?

I assume it is not actually the IPV6 causing the issue, but rather something in my setup.

These are the critical (I think) files I have modified:

named.conf.local

zone "ourdomain.inc" {
        type master;
        file "/etc/bind/zones/ourdomain.inc.db";
};
zone "201.168.192.in-addr.arpa" {
        type master;
        file "/etc/bind/zones/rev.201.168.192.in-addr.arpa";
};

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 {
                1.2.3.4; //IP of our external DNS provider
        };

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

ourdomain.inc.db

$TTL 86400
ourdomain.inc.      IN      SOA     ns1.ipower.com. admin.ourdomain.inc. (
                                                        2006081401
                                                        28800
                                                        3600
                                                        604800
                                                        38400
)
serv1                IN      A               192.168.201.223
serv2                IN      A               192.168.201.220
serv3         IN      A               192.168.201.219
ns1.ipower.com.      IN      A               1.2.3.4
ns2.ipower.com.      IN      A               1.2.3.5
@                    IN      NS              ns1.ipower.com.
@                    IN      NS              ns2.ipower.com.
svn                  IN      CNAME           serv1
docs                 IN      CNAME           serv2
jira                 IN      CNAME           serv3
confluence           IN      CNAME           serv3
fisheye              IN      CNAME           serv3

rev.201.168.192.in-addr.arpa

$TTL 86400
201.168.192.in-addr.arpa. IN SOA ns1.ipower.com. admin.ourdomain.inc. (
                        2006081401;
                        28800;
                        604800;
                        604800;
                        86400
)

223                    IN    PTR    serv1
@                      IN    NS     ns1.ipower.com.
@                      IN    NS     ns2.ipower.com.

named.conf

include "/etc/bind/named.conf.options";
include "/etc/bind/named.conf.local";
include "/etc/bind/named.conf.default-zones";

I then made our internal DNS my preferred DNS with the two external DNSs the next in-line. More the most part this seems to work, I can ping svn.ourdomain.inc and it resolves to the correct IP, I can also ping google.com and it also resolves no problem. So all seem good.

However, periodically (couple of times a day at least), I loose the ability to ping the svn.domain.inc (and all others defined under the internal DNS). What seem to fix the issue temporarily is to disable IPV6 on the network adapter of the client machine and then re-enable it. Then it works for a bit but will always fail again.

System Info

Internal DNS

Distributor ID: Debian
Description:    Debian GNU/Linux 6.0.6 (squeeze)
Release:        6.0.6
Codename:       squeeze

Linux 2.6.32-5-686 i686

BIND 9.7.3

PC

OS Name:                   Microsoft Windows 7 Professional
OS Version:                6.1.7601 Service Pack 1 Build 7601
System Type:               x64-based PC

Network Card(s):           2 NIC(s) Installed.
                           [01]: Realtek PCIe GBE Family Controller
                                 Connection Name: WORK LAN
                                 DHCP Enabled:    No
                                 IP address(es)
                                 [01]: the.ipv4.address
                                 [02]: the:ipv6:address

The question...

So based on my files above and the symptoms I described; what effect could IPV6 be having on my setup? What can I do to fix this?

I assume it is not actually the IPV6 causing the issue, but rather something in my setup.