---
title: "Short note: FTP"
subject: "Web Technology"
chapter: 2
key: "semester_7/web_technology:short-note-ftp"
source: https://www.bctengineer.com/q/semester_7/web_technology/short-note-ftp
site: BCT Engineering
---

# Short note: FTP

Web Technology · Chapter 2: Web basics

- Asked in: 2074 Asoj, 3 marks
- Video: [FTP (File Transfer Protocol), SFTP, TFTP Explained.](https://www.youtube.com/watch?v=tOj8MSEIbfA) — PowerCert Animated Videos
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/web_technology/short-note-ftp
- Whole chapter: https://www.bctengineer.com/md/semester_7/web_technology/chapter-2

## Question

Write a short note on FTP (File Transfer Protocol).

## Short answer

FTP is a TCP-based protocol for transferring files using a control connection on port 21 and a data connection on port 20. It requires authentication but sends passwords in plain text, so SFTP or FTPS are recommended.

## Answer

**FTP (File Transfer Protocol)** is an application-layer, TCP-based protocol used to transfer files between a client and a server over a network. It is defined in RFC 959 and uses the client-server model.

#### Key features
- Uses **two connections**: a *control connection* on port **21** (commands and replies such as `USER`, `PASS`, `LIST`, `RETR`, `STOR`) and a *data connection* on port **20** (active mode) or a negotiated port (passive mode) for the actual file transfer.
- Needs a user name and password, though **anonymous FTP** allows public downloads.
- Supports upload (`put/STOR`), download (`get/RETR`), directory listing, rename and delete.
- Transfer modes: ASCII (text) and binary (images, programs).

```text
FTP client                        FTP server
   |==== control (port 21) ==========|
   |---- USER / PASS / RETR file --->|
   |<=== data connection ============|
   |        (file contents)          |
```

#### Uses
Uploading web pages to a web server, distributing software and sharing large files.

#### Limitations
Data, including passwords, is sent in **plain text**, so it is insecure. Secure alternatives are **SFTP** (over SSH) and **FTPS** (FTP over TLS). Popular clients: FileZilla, WinSCP, and the command-line `ftp`.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. How many connections does FTP use and for what?
   A. One connection on port 80
   B. Two both on port 21 for email
   C. Three: control, data and DNS
   D. Two: control (port 21) for commands and data for file transfer
   Answer: D. FTP separates commands from file data. (Key point: Two connections)

2. Why is FTP insecure?
   A. Data and passwords are sent in plain text
   B. It uses UDP
   C. It has no passwords
   D. It encrypts too weakly
   Answer: A. Secure alternatives are SFTP (SSH) and FTPS (TLS). (Key point: Insecurity)

3. What does anonymous FTP allow?
   A. Unlimited uploads
   B. Public downloads without a personal account
   C. Encrypted transfers
   D. Email sending
   Answer: B. Anonymous FTP lets anyone download public files. (Key point: Anonymous FTP)

## Related in other subjects

- [Short note: SMTP](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Asmtp-note) — Computer Networks and Security, chapter 6
- [SS7 vs OSI; MTP-L2 signal units](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Ass7-vs-osi-mtp2-units) — Telecommunications, chapter 5