troubleshooting Question

BIND Slave Not Working when Master is Down

Avatar of DanJourno
DanJournoFlag for United Kingdom of Great Britain and Northern Ireland asked on
Linux
6 Comments1 Solution1940 ViewsLast Modified:
Hi,

I have a Master DNS server running on Windows 2008 and a Slave DNS server running BIND on Linux.

The slave successfully collects the zone files from the master server, and can serve dns lookup requests fine.

However, recently the Master DNS server went down and I found that the slave also stopped working. When I run a test on the slave server using nslookup, it said

server can't find www.domain.com: SERVFAIL

The zone TTL is very low (2 minutes) to ensure we can switch to a backup server quite quickly. In the event that the Master server goes down, how can I ensure that the slave server keeps running, even when the zone files become old?

Here are the settings from windows

DNS Screenshot
And a copy of the zone file from the slave server

$ORIGIN .
$TTL 120        ; 2 minutes
domain.com IN SOA ns5.domain.com. hostmaster.domain.com. (
                                2012012061 ; serial
                                120        ; refresh (2 minutes)
                                120        ; retry (2 minutes)
                                120        ; expire (2 minutes)
                                120        ; minimum (2 minutes)
                                )
$TTL 86400      ; 1 day
                        NS      ns5.domain.com.
                        NS      sip2.domain.com.
$TTL 120        ; 2 minutes
                        A       **.222.**.254
                        MX      10 spam3.domain.net.
                        MX      10 spam4.domain.net.
$ORIGIN domain.com.
autodiscover            A       **.46.**.17
backupmx                A       **.222.**.224
ftp                     A       **.222.**.254
mail                    A       **.222.**.254
my                      A       **.222.**.254
ns1                     A       **.222.**.254
ns2                     A       **.222.**.51
ns5                     A       **.222.**.254
ns6                     A       **.222.**.51
pop3                    A       **.222.**.254
sip1                    A       **.222.**.126
$TTL 86400      ; 1 day
sip2                    A       **.250.**.36
$TTL 120        ; 2 minutes
sipprovisioning         A       **.222.**.254
sipserver               A       **.222.**.126
smtp                    A       **.222.**.254
webmail                 A       **.222.**.254
webserver1              A       **.222.**.254
www                     A       **.222.**.254

The goals are...
1) To keep TTL at 2 minutes to ensure we can make instant changes to our domains.
2) To ensure the slave server keeps zone files for at least 2 days when the primary server is offline.

Thanks
Dan
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