---
title: "Internet vs Intranet and DNS need"
subject: "Internet and Intranet"
chapter: 1
key: "semester_8/internet_and_intranet:internet-intranet-compare-dns"
source: https://www.bctengineer.com/q/semester_8/internet_and_intranet/internet-intranet-compare-dns
site: BCT Engineering
---

# Internet vs Intranet and DNS need

Internet and Intranet · Chapter 1: Introduction

- Asked in: 2073 Magh, 4+4 marks
- Video: [Types of Internetworking | Internet, Intranet & Extranet](https://www.youtube.com/watch?v=W38Pe8CVWNA) — Perfect Computer Engineer
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/internet_and_intranet/internet-intranet-compare-dns
- Whole chapter: https://www.bctengineer.com/md/semester_8/internet_and_intranet/chapter-1

## Question

Define and compare Internet and Intranet. Discuss the need and use of Domain Name system (DNS) over the internet.

## Short answer

Internet is a global public TCP/IP network; Intranet is a private network using same technologies within an organization, firewalled. DNS, a hierarchical distributed database, translates domain names to IP addresses. It is needed because names are memorable and allow IP changes without user impact. Key uses: A/AAAA for web, MX for mail, PTR for reverse, CNAME for aliasing, SRV/TXT for service discovery.

## Answer

#### Internet

The **Internet** is the global public network of interconnected networks, using TCP/IP, which anyone with access can use. It is not owned by one organisation.

#### Intranet

An **intranet** is a private network that uses Internet technologies (TCP/IP, HTTP, web browsers, e-mail) but is owned by and limited to one organisation and its authorised users. It is normally protected from the Internet by a firewall.

| Basis | Internet | Intranet |
|---|---|---|
| Scope | Global | Within one organisation |
| Ownership | No single owner | Owned and managed by the organisation |
| Access | Public, anyone | Restricted to employees/members |
| Security | Low; open to attacks | High; firewall, authentication |
| Content | Any information | Organisational information (policies, HR, internal apps) |
| Addresses | Public IPs | Private IPs (10.x, 172.16-31.x, 192.168.x) |
| Speed/control | Depends on ISPs, shared | Faster; the organisation controls bandwidth |
| Cost | ISP charges, shared infrastructure | Cost of setup and maintenance by the organisation |

#### Need and use of DNS

The **Domain Name System (DNS)** is a distributed, hierarchical database that translates domain names (www.tu.edu.np) to IP addresses (and back).

**Need:** computers use IP addresses, but people remember names more easily. Also, a site's IP address can change while its name stays the same. A single flat host file cannot scale to billions of hosts, so DNS is distributed.

**Structure:** root servers, then top-level domains (.com, .org, .np), then second-level domains (edu.np) and lower-level domains (tu.edu.np). Zones are managed by authoritative name servers.

**How it works:**
1. The browser asks the local resolver (ISP DNS) for the IP of the name.
2. If not cached, the resolver asks a root server, then the TLD server, then the authoritative server, which returns the IP.
3. The resolver caches the answer and replies to the client.

**Uses:**
- Web browsing: names to IP (A and AAAA records).
- E-mail routing using MX records.
- Reverse lookup (PTR) for logging and spam checks.
- Load balancing and aliases (CNAME), moving servers without changing the name.
- Service discovery (SRV) and verification (TXT, SPF).

## Check yourself

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

1. What is an intranet?
   A. A private network using Internet technologies, owned by and limited to one organisation and its authorised users, normally protected by a firewall
   B. A public network owned by ISPs
   C. A network of only Tier-1 ISPs
   D. Another name for a VPN provider
   Answer: A. Intranets use TCP/IP, HTTP and browsers but are restricted to one organisation. (Key point: Intranet definition)

2. Why is DNS needed?
   A. Computers use names and people use IP addresses
   B. A flat host file scales best to billions of hosts
   C. To assign IP addresses to routers
   D. People remember names more easily than IP addresses, and a site's IP can change while its name stays the same
   Answer: D. DNS maps names to IPs; being distributed and hierarchical, it scales where a single host file cannot. (Key point: Need for DNS)

3. If the local resolver has no cached answer, what is the order of queries?
   A. Authoritative server, TLD server, root server
   B. Root server, then TLD server, then authoritative server
   C. TLD server, root server, then client
   D. Root server, authoritative server, then TLD server
   Answer: B. The resolver follows the hierarchy: root, TLD, then authoritative, and then caches the answer. (Key point: DNS resolution sequence)

4. Which record type is used for e-mail routing?
   A. PTR
   B. CNAME
   C. MX
   D. AAAA
   Answer: C. MX records identify mail servers; PTR is reverse lookup and CNAME is an alias. (Key point: DNS record types)

## Related in Internet and Intranet

- [Need and services of DNS](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Adns-need-services) — Internet and Intranet, chapter 3
- [Intranet vs Internet, firewall, content filtering](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aintranet-internet-benefits-firewall) — Internet and Intranet, chapter 1
- [Intranet vs Internet and intranet protocols](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aintranet-vs-internet-protocols) — Internet and Intranet, chapter 1
- [Intranet, Internet, Extranet comparison and resources](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aintranet-internet-extranet-compare) — Internet and Intranet, chapter 1
- [Virtual hosting types; name-based steps](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Avirtual-hosting-types-named-steps) — Internet and Intranet, chapter 4, asked 2×
- [Intranet implementation procedure and VPN](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aintranet-implementation-procedure-vpn) — Internet and Intranet, chapter 6

## Related in other subjects

- [Internet, intranet and extranet use](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Ainternet-intranet-extranet) — Information System, chapter 1
- [Short note: Internet / Intranet](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Ashort-note-internet-intranet) — Basic Electronics Engineering, chapter 5
- [Application, system and device domain](https://www.bctengineer.com/question.md?key=semester_8%2Fmultimedia_system%3Aapplication-system-device-domain) — Multimedia System, chapter 1
- [DNS and its working mechanism](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Adns-working) — Distributed System, chapter 2, asked 3×