Victor Stodell

This week we stumbled upon some weirdness in our new 2008 R2 DNS servers. A couple of URLs, for example www.smhi.se and www.stockholm.se could not be resolved from a 2008 R2 server. The existing 2003 servers with the same configuration worked perfectly. After thorough troubleshooting we found out that there is a new default setting in Windows Server 2008 R2 regarding the  EDNS-protocol  that caused the issues. Not all of the DNS servers around the internet are able to handle  EDNS , but in 2008 R2 this protocol is enabled by default. Normally you would think there is a fallback mechanism to standard DNS protocol if an EDNS request fails, but Windows Server does not have that. The solution was simply to disable EDNS by using the command: dnscmd /config /EnableEDNSProbes 0 Scott Forsyth has written more about this issue and how he found the solution: http://weblogs.asp.net/owscott/archive/2009/09/15/windows-server-2008-r2-dns-issues.aspx

With the purpose of automation DNS documentation I needed to get information programatically from the DNS servers. The answer to this, and many other similar tasks is spelled  WMI . That is short for  Windows Management Instrumentation , which is an infrastructure for getting information from Windows using a specific query language. Here is a method to get the host names and IP addresses for each A-record on the specified domain. public string Server = "192.168.0.1"; public string Domain = "domain.local"; public string Username = "DOMAIN\User"; public string Password = "Pa$$w0rd"; public Dictionary<string, string> GetHosts() { Dictionary<string, string> hosts = new Dictionary<string, string>(); ManagementScope scope = new ManagementScope(String.Format(@"\\{0}\Root\MicrosoftDNS", Server)); scope.Options.Impersonation = ImpersonationLevel.Impersonate; scope.Options.Username = Username; scope.Opti...