- 2073 Magh · 4+4 marks
Internet vs Intranet and DNS need
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.
Define and compare Internet and Intranet. Discuss the need and use of Domain Name system (DNS) over the internet.
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:
- The browser asks the local resolver (ISP DNS) for the IP of the name.
- If not cached, the resolver asks a root server, then the TLD server, then the authoritative server, which returns the IP.
- 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).
✓ Answer checked by Claude Opus 5.5 (high effort)
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