--- title: "RFC role and IPv6 addressing" subject: "Internet and Intranet" chapter: 2 key: "semester_8/internet_and_intranet:rfc-development-ipv6-addressing" source: https://www.bctengineer.com/q/semester_8/internet_and_intranet/rfc-development-ipv6-addressing site: BCT Engineering --- # RFC role and IPv6 addressing Internet and Intranet · Chapter 2: Internet Protocol Overview - Asked in: 2072 Magh, 4+6 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/internet_and_intranet/rfc-development-ipv6-addressing - Whole chapter: https://www.bctengineer.com/md/semester_8/internet_and_intranet/chapter-2 ## Question How has RFC helped in the development and distribution of internet? Write about IPv6 addressing in detail. ## Short answer RFCs are permanent, free, open specifications enabling interoperability and global Internet distribution. IPv6 has 128-bit addresses, written in eight colon-separated hex groups (shortenable with ::), prefix/length format. Types: global unicast (2000::/3), link-local (fe80::/10), multicast (ff00::/8), loopback (::1/128); no broadcast. Interface IDs can use EUI-64 from MAC; SLAAC or DHCPv6 for config; sites get /48. ## Answer #### Role of RFCs in the development and distribution of the Internet A Request for Comments (RFC) is a numbered, public document that specifies an Internet protocol or practice. RFCs helped the Internet grow in these ways: 1. **Open standards:** every protocol (TCP RFC 793, IP RFC 791, HTTP, SMTP RFC 5321, DNS RFC 1035, IPv6 RFC 8200) is described in a free public document, so any vendor can build compatible products. 2. **Interoperability:** equipment from different manufacturers works together because all follow the same specification. 3. **Community review:** the "request for comments" process lets engineers worldwide review and improve a design before it becomes a standard. 4. **Easy distribution:** RFCs are freely available online, so developers in any country, including Nepal, can implement the protocols without licence fees. 5. **Documentation of history and practice:** informational, BCP and experimental RFCs record operational experience and guide new work. 6. **Stable versioning:** RFC numbers never change; updates are new RFCs, so implementers always know which version they follow. #### IPv6 addressing in detail IPv6 (RFC 8200 for the protocol, RFC 4291 for addressing) uses **128-bit** addresses, giving about 3.4 x 10^38 addresses. **Notation:** eight groups of four hexadecimal digits separated by colons, e.g. `2001:0db8:0000:0000:0000:0000:0000:0001`. Short-hand rules: - Leading zeros in a group may be dropped: `2001:db8:0:0:0:0:0:1` - One run of all-zero groups may be replaced by `::` (only once): `2001:db8::1` **Structure:** prefix/length, like CIDR, e.g. `2001:db8:abcd:12::/64`. A typical global unicast address is a 48-bit site prefix, a 16-bit subnet ID and a 64-bit interface ID. ```text | 48 bits | 16 bits | 64 bits | | Global prefix |Subnet ID| Interface ID | ``` **Address types** | Type | Prefix | Purpose | |---|---|---| | Global unicast | 2000::/3 | One-to-one, routable on the Internet | | Link-local | fe80::/10 | Used on one link only, auto-configured | | Unique local | fc00::/7 | Private use inside an organisation | | Multicast | ff00::/8 | One-to-many, replaces broadcast | | Anycast | from unicast range | Same address on many nodes; nearest one answers | | Loopback | ::1/128 | Local host | | Unspecified | ::/128 | Used before an address is assigned | There is **no broadcast** in IPv6. **Interface ID and auto-configuration:** the 64-bit interface ID can be built from the MAC address by EUI-64: split the MAC, insert `ff:fe` in the middle and flip the 7th bit. For MAC `00:1A:2B:3C:4D:5E` the interface ID is `021A:2BFF:FE3C:4D5E`. Hosts get addresses by **SLAAC** (Router Advertisement gives the prefix) or **DHCPv6**. Neighbour Discovery (ICMPv6) replaces ARP. **Allocation:** IANA gives RIRs /12 blocks, RIRs give ISPs /32, and ISPs give each customer site a /48 (or /56 for homes). ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. How do RFCs help vendors and developers worldwide build Internet products? A. They are free public specifications, so any vendor can build compatible products without licence fees B. They are licensed documents sold to certified vendors only C. They are rewritten by each vendor to suit its own equipment D. They apply only to protocols used inside the United States Answer: A. RFCs are freely available online, so anyone can implement the protocols and equipment from different makers interoperates. (Key point: Open, freely available standards) 2. What happens when a published RFC needs to be changed or improved? A. The original RFC is edited and keeps its number B. A new RFC with a new number updates or replaces it; the old number never changes C. The RFC number is reassigned to the new text D. The RFC is deleted from the archive Answer: B. RFC numbers never change, so implementers always know exactly which version they follow. (Key point: Stable RFC versioning) 3. Which is a valid short form of 2001:0db8:0000:0000:0000:0000:0000:0001? A. 2001:db8::1:: B. 2001:db8:1 C. 2001:db8::1 D. 2001::db8::1 Answer: C. Leading zeros can be dropped and one run of all-zero groups can be replaced by :: (only once), giving 2001:db8::1. (Key point: IPv6 address shorthand) 4. A typical IPv6 global unicast address is split into which parts? A. 64-bit prefix, 16-bit subnet ID, 48-bit interface ID B. 48-bit site prefix, 16-bit subnet ID, 64-bit interface ID C. 32-bit network, 32-bit host, 64-bit port D. 16-bit prefix, 48-bit subnet ID, 64-bit interface ID Answer: B. 48 + 16 + 64 = 128 bits: site prefix, subnet ID and interface ID. (Key point: Global unicast structure) 5. How is a 64-bit interface ID built from a 48-bit MAC address by EUI-64? A. Insert ff:fe in the middle of the MAC and flip the 7th bit B. Append 16 zero bits and keep the MAC unchanged C. Hash the MAC with SHA-1 D. Insert ff:ff at the start and flip the last bit Answer: A. The MAC is split in half, ff:fe is inserted, and the 7th bit is flipped (00:1A:2B:3C:4D:5E becomes 021A:2BFF:FE3C:4D5E). (Key point: EUI-64 interface ID) ## Related in Internet and Intranet - [RFC and IPv4/IPv6 fragmentation](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Arfc-fragmentation-ipv4-ipv6) — Internet and Intranet, chapter 2 - [IPv6 features, header format, RFC streams](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aipv6-features-header-rfc) — Internet and Intranet, chapter 2 - [IPv6 migration; IPv4 vs IPv6 packet structure](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aipv6-migration-router-packet) — Internet and Intranet, chapter 2 - [History and development of Internet](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Ainternet-history-development) — Internet and Intranet, chapter 1 - [RFC management by streams and status](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Arfc-streams-status) — Internet and Intranet, chapter 1 - [IPv4 vs IPv6 datagram fragmentation](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aipv4-ipv6-fragmentation) — Internet and Intranet, chapter 2, asked 2× ## Related in other subjects - [Role of electrical energy in sustainable development](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Aelectrical-energy-sustainable-development) — Utilization of Electrical Energy, chapter 1, asked 2× - [Role of groundwater in irrigation development](https://www.bctengineer.com/question.md?key=semester_5%2Fengineering_hydrology%3Agroundwater-irrigation-role) — Engineering Hydrology, chapter 1 - [Factors for IPv6; IPv4 to IPv6 transition](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Aipv6-factors-transition) — Computer Networks and Security, chapter 7, asked 2× - [Internet structure: repeater, bridge, router, gateway](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Ainternet-structure-devices) — Telecommunications, chapter 8