[Samba] DNS update - NT_STATUS_IO_TIMEOUT every 10 minutes

Rick Schauer rick.schauer at dualhelix.net
Wed Aug 27 23:11:06 MDT 2014

I have an unusual problem that I can't seem to figure out. 


As a background I had to rebuild my Samba4 AD DC from scratch, since my USB
stick went out.  The Samba4 AD DC is now running on a Raspberry Pi with the
root file system on an external USB hard drive.  It also has an email server
using postfix/dovecot/spamassassin on it too.  It's very cool to have an AD
DC and email server running on a low powered Raspberry Pi.  Saves a few $ a
month on my electric bill.


So I tried grabbing the latest Samba4 from the apt-get repository, which was
version 4.0.  It still had issues, so I removed that version, and then I
downloaded the 4.1.11 stable release from the git repository.  I compiled
and installed Samba 4 without problem.  I ran the samba-tool provision and
checked my configuration.  All seemed well.   I am using the internal DNS
that comes with Samba4.  I ran all the tests from the instructions on the
Samba Wiki page.  https://wiki.samba.org/index.php/Samba_AD_DC_HOWTO.  The
smbclient, Kerberos and DNS tests all work fine.   


I then created two users and joined 2 Windows 7, 2 Windows XP, and one Linux
Mint 13 client to the domain.   I'm able to log into the domain from all
workstations.  I can update the domain using the Windows domain tools from
my Windows 7 client without issue.  


I did have some ipv6 binding errors, so I set the interfaces and bind
interfaces only settings in the smb.conf to get rid of them, since I'm not
using ipv6.  

The only issue now is I keep getting the following error messages that
appear every 10 minutes in the samba log files:


[2014/08/27 20:00:13.783274,  0]

  ../source4/dsdb/dns/dns_update.c:294: Failed DNS update -

[2014/08/27 20:00:13.854986,  0]

  ../source4/dsdb/dns/dns_update.c:323: Failed SPN update -


It starts about 20 seconds after Samba starts up, and then 10 minute
intervals thereafter. 


I ran the debug level 5 to see if it helped, but I don't see anything
useful.  These errors show up in between DNS queries from the workstations.

I'm not that familiar with how the internal Samba DNS works, or what it's
trying to do.   

Again everything is working fine, with the exception of this error filling
up my log files.  


I could live with it if need be, but it's bugging me.  Any suggestion would
be most helpful.  

I checked the samba list archives, but found nothing useful.



smb.conf (domain name X'ed out): 


# Global parameters


        workgroup = XXXX

        realm = XXXX.LOCAL

        netbios name = SERVER1

        server role = active directory domain controller

        dns forwarder =

        idmap_ldb:use rfc2307 = yes

        interfaces =

        bind interfaces only = yes


        #log level = 5

        #log file = /usr/local/samba/var/sambadebug.log



        path = /usr/local/samba/var/locks/sysvol/xxxx.local/scripts

        read only = No



        path = /usr/local/samba/var/locks/sysvol

        read only = No




domain xxxx.local

search xxxx.local




hosts:       localhost.xxxx.local localhost     server1.xxxx.local server1







passwd:         compat

group:          compat

shadow:         compat


hosts:          files dns mdns4_minimal [NOTFOUND=return] mdns4

networks:       files


protocols:      db files

services:       db files

ethers:         db files

rpc:            db files


netgroup:       nis






        default_realm = XXXX.LOCAL

        dns_lookup_realm = false

        dns_lookup_kdc = true



        XXXX.LOCAL = {

                kdc = server1

                admin_server = server1




        .xxxx.local = XXXX.LOCAL



Rick Schauer


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