I've discovered that class SPWebApplication doesn't exists in SharePoint 2003 API(Microsoft.SharePoint.dll, version 11, namespace Microsoft.SharePoint.Administration). But is there any analog of it? How can i retrieve IsAdministrationWebApplication property for example? Or SharePoint 2003 doesn't contain such options at all?
Possibly you're looking for AdminPortUrl property of the SPWebServer class, which is described as: