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Application Presentation Session
PGP works at the Layer 6 - Presentation level.
Session and Presentation Layers
HTTP would fall into either the Application layer or the Presentation layer. There are conflicting views as to which layer protocols like HTTP belong to, but it would be one of those two.
Layer 5 - Session layer
Network Layer
I assume you're talking about portion of the OSI model that handles character-encoding such as ASCII. It is the Presentation Layer of the OSI model.
Presentation
It's called Presentation layer.
application
No. Only protocols that users can see on their screen are considered Presentation Layer based. Hubs and repeaters operate on the physical layer, because it doesn't do anything with the data, it simply forwards it.
smtp(simple mail transfer protocol,),ftp,(file trasfer protocol),ip(nternet protocol).