SBS2008 causing DNS resolution issues RRS feed

  • Question

  • Hi all, I'm having an issue with DNS on my home network when a particular SBS2008 server is on the same network. In particular I have noticed that "the internet stops working" without any apparent cause. nslookup helpfully demonstrates that the problem is in name resolution, my router (which acts as DHCP and DNS server) fails to look up anything. If I change the DNS server on my network connection to directly go to the google public DNS server, everything works fine on this machine. Obviously this workaround is not practical for a whole network or consumer devices like phones and iPads.

    I have further narrowed this down, in that it tends to happen almost exactly 4 hours after the SBS2008 server is brought up. I verified this recently by jumping over to my hypervisor when I noticed the problem and seeing that the uptime on that server was four hours and six minutes.

    I have disabled the DNS Server service (set its startup type to "Disabled"). I even tried adjusting the firewall on that server to block DNS traffic.

    I don't understand how it has any effect at all. My DNS server is clearly set to the router, and when I go into its admin interface it says that its DNS server is a public IP which I assume to be my ISPs DNS server. I currently have that server turned off, and for the last week haven't had any troubles at all until yesterday when I turned it on (because I needed to log on to a server in that domain which had no DC). Four hours and six minutes later, "the internet stopped working".

    There is a server rack on the network with an amount of kit, I do operate a business from home. To explain the topology;

    The network isn't ordinarily part of a domain however obviously the SBS server is hosting a domain, and there are two other servers attached to that domain. Both the domain and the rest of the network share the same subnet and infrastructure, and there is no managed switching in the process.

    The SBS server is virtualised in Hyper-V 2012, and was originally built virtual on an ESX host until a recent migration. NOTE the problem existed before and after the migration.

    The other two servers in the domain are Server 2008 and Server 2003, with no domain features on either of them. the 2008 server is a Terminal Server. There used to be a small office of PCs and Laptops in the domain, however they're all gone now.

    Also on the network are two physical Server 2012 instances - one of which is the Hyper-V host for all three of the servers above and the other is a public facing development web server.

    In addition, there are a small number of other Hyper-V client systems, the only one that is up 24/7 is a Server 2012 instance with Team Foundation Server. The others are raised and dropped as needed but are a mixture of XP, Windows 7, Windows 8 clients and an SBS2011 test machine (note this SBS2011 instance was first created after the problems were noted and it is almost never turned on).

    Lastly there are a number of consumer devices on the network, two NAS, an iPhone, a Windows Phone, several Windows 8 clients, sometimes some iPads, a wireless printer, and occasionally any random customer machine may be given network access to download updates or software. In terms of infrastructure, all of the servers and NAS are on a cisco unmanaged small business switch, which is connected to a simple ADSL2+ modem/router with wifi (Netgear DGND3700v2).

    Okay, apologies for the rambling but I like to be thorough.

    If anybody has any ideas, I'd really like to be able to have this server on more often without losing my access to outside.


    • Edited by Jeff Whitty Wednesday, March 26, 2014 6:19 AM
    Wednesday, March 26, 2014 4:07 AM

All replies

  • Simple answer, SBS servers do not like other DHCP Server and DNS Server devices on the network, unless configured to work with them. I just had this same issue with a client, who was getting VoIP installed and the installer configured DHCP and DNS onto the firewall, once he did that, within about 30min, everything halted and devices stopped talking to each other, no internet, etc. And my luck I happened to be golfing when this went down, had to talk them through fixing it, while I played.

    Disabling DHCP and DNS on the SBS is not a real option as SBS configures itself to look at itself for DHCP and DNS resolution, disabling those services will cause other problems within the server.

    • Marked as answer by Andy QiModerator Wednesday, April 9, 2014 2:40 AM
    • Unmarked as answer by Jeff Whitty Tuesday, April 15, 2014 2:21 AM
    Wednesday, March 26, 2014 3:54 PM
  • Thanks, that validates my issue and confirms my diagnosis. Now, is there anything I can do to SBS to stop it causing the issue?
    Tuesday, April 1, 2014 1:53 AM