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Q1. If my application such as MS office in standalone computer and without access internet. Will this application need to use application layer in internet model.

Application layer in Internet model consists of presentation layer, session layer and application layer.

What software is using application layer?

Q2. FTP is example of application for application layer in internet model?

Q3. file transfer, email, define compatible representation of all data are the service provided by applicatio layer in internet model?

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  • Latest Post Latest Post by wmrandall

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Short clarification anchored to the original questions from and the timeout note from :

A) “Application layer” in the Internet (TCP/IP) sense means the network-facing protocols and services (the things that speak HTTP, FTP, SMTP, DNS, etc.), not every piece of software that runs at user level. The Internet protocol suite intentionally combines the OSI Presentation and Session responsibilities into a single application layer, so the phrase can mean different things depending on whether someone is using the OSI teaching model or the TCP/IP model. (datatracker.ietf.org)

B) A standalone copy of an office program that never contacts another machine (no updates, no cloud sync, no activation checks) will not use those network application‑layer protocols; it will only use local OS services (file I/O, GUI, local libraries). When the same program tries to reach a network service (auto‑update, OneDrive, license servers) it then acts as an application‑layer client and will show the blocking/timeout behaviour mentioned by . (datatracker.ietf.org)

C) Yes — FTP is an application‑layer protocol (see RFC 959). Likewise, e‑mail transport is handled by application‑layer protocols (SMTP is defined in RFC 5321). Those protocols run on top of transport protocols (TCP/UDP). (rfc-editor.org)

D) “Presentation” tasks (data formats, attachments, character encodings) are typically implemented by application‑level standards or helper specs (for example MIME for message bodies), and encryption/compression is commonly provided by separate protocols or libraries (for example TLS). In the TCP/IP world these functions live where the application designers place them, not in a separate OSI layer. (rfc-editor.org)

Practical takeaway (concise): file transfer and e‑mail are classic application‑layer services; an app only engages them when it actually needs network I/O. If an app “freezes” with no network, it’s usually waiting on a remote service or a socket timeout — that’s expected behaviour when network dependencies exist.

Member Avatar for wmrandall

here's a start on understanding the layers: http://www.inetdaemon.com/tutorials/basic_concepts/network_models/osi_model/

short answer: any application that attempts to access the internet, for updates, status reporting, fetching, uploading, etc will timeout if it can't get an answer from the target website. Some apps use default timeouts of up to two minutes, so it can seem that the app or computer is "frozen". Same for http, or ftp, or even gateway protocols.

The app will work in its basic functionality, only. Some internet-based apps won't work at all (e.g;

X-Lite).

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