A Multi-tier Web Application includes 4 layers:
- Web Layer (Presentation Layer)
- Business Rules Layer
- Data Access Layer
From the post in , the author based on the Microsoft Architecture exams and has a conclusion that Multi-Tiers are either physical or logical, physical being “machines”, such as client – server and logical being the layers Presentation, Business Logic and Data Access.
Internet explorer and IIS count as tiers anyway, so yes you are multi tier.
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 Building a Multi-Tier Web Application in the .NET 3.5 Framework Using LINQ to SQL, The Code Project, http://www.codeproject.com/KB/aspnet/NTierApp_UsingLINQ.aspx, retrieved in 13/08/2010
 Three-Tier Architecture, Linux Journal, http://www.linuxjournal.com/article/3508?page=0,2, accessed in 13/08/2010
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