I would like to get a user's group memberships in an ActiveDirectory, without being in the domain. When I run this inside the domain, all is well.

var context = new PrincipalContext(ContextType.Domain);
var principal = UserPrincipal.FindByIdentity(context, IdentityType.Name, "administrator");

foreach (var authorizationGroup in principal.GetAuthorizationGroups())
{
    Console.WriteLine(authorizationGroup.Name);
}

However, when I run outside the domain, I have to specify the PrincipalContext lie this:

var context = new PrincipalContext(ContextType.Domain, "10.0.1.255", "DC=test,DC=ad,DC=be", "administrator", "password");

When I run this code, I get an exception when I execute principal.GetAuthorizationGroups(). The exception I get is:

System.DirectoryServices.AccountManagement.PrincipalOperationException: Information about the domain could not be retrieved (1355).
at System.DirectoryServices.AccountManagement.Utils.GetDcName(String computerName, String domainName, String siteName, Int32 flags)
at System.DirectoryServices.AccountManagement.ADStoreCtx.LoadDomainInfo()
at System.DirectoryServices.AccountManagement.ADStoreCtx.get_DnsDomainName()
at System.DirectoryServices.AccountManagement.ADStoreCtx.GetGroupsMemberOfAZ(Principal p)
at System.DirectoryServices.AccountManagement.UserPrincipal.GetAuthorizationGroupsHelper()
at System.DirectoryServices.AccountManagement.UserPrincipal.GetAuthorizationGroups()