Data communication and network...

1. Optical fibres use total internal reflection to transfer data. The primary condition for total internal reflection is that the signal must travel from an optically denser medium to an optically rarer medium. Secondly, the angle of incidence must be greater than the critical angle.

1. UPI (Unified Payments Interface): UPI is a mobile-based payment system that allows users to transfer money from their bank accounts to any other bank account instantly and securely.

2. As a UPI user, you have to create a unique identifier called UPI ID. It is linked to your bank account. With its help, money can be easily sent and received from the bank account. For this, you do not need to share your account number or other information.

The search engine performs the following tasks-

1. Web crawling: Search engines search all web pages on the web using a crawler. A crawler is a program that finds new web pages by following links on the web.

2. Indexing: Once the crawler finds all the web pages, the search engine indexes them in a database. The index contains information for each web page, such as title, URL, and content.

3. Searching: When a user types a search query, the search engine searches all the web pages in the index that may be related to the query.

1. Junk email is called spam. Spam is an email that you did not request, and which usually promotes advertising or other unwanted content.

2. Spoofing is a special type of cyber-attack in which someone attempts to deceive other computer networks by using a computer, device, or network to identify themselves as a legitimate entity.

1. The full name of FTP is File Transfer Protocol.

2. It is a network protocol used to transfer files between two computers.

3. FTP is a two-way protocol, which means both computers can send and receive files from each other.

4. FTP runs in two main modes-

- Unprotected Mode: This mode transfers files without any protection.

- Secure Mode: This mode uses encryption to transfer files using SSL or TLS.