Computer Networks Module 9
IPv6 interview questions
4 interview questions on IPv6 from Computer Networks: short warm-ups, then what each harder question tests, the first step of a good answer and its follow-ups.
Warm-up questions
Short questions with short answers, each answered in full.
-
Fresher to mid
What does
::mean in an IPv6 address, and why may it appear only once? -
Fresher to mid
Why does every IPv6 LAN get a /64, when no LAN has anywhere near 2⁶⁴ hosts?
Questions with model answers
What each question tests, the first step of a good answer and the follow-ups to expect.
-
Mid to senior
Your company receives 2001:db8:4d00::/48. It has 3 campuses, each with up to 12 buildings, and up to 60 VLANs in a building, and it expects to grow. Design the subnet plan and defend the bit layout.
- What it tests
- Planning the 16-bit subnet ID in whole hex digits, leaving room to grow, keeping every level summarisable for routes, firewall rules and reverse DNS, and reserving space for infrastructure.
- First step
- Count the bits each level needs and round up to whole hex digits: 3 campuses fit in one digit, 12 buildings in one digit, 60 VLANs in two digits. That uses all 16 bits of the subnet ID, so check where the growth fits and what to reserve for routers and links before you commit to it.
- Follow-ups
-
- A fourth and a fifth campus open next year. Does the plan survive?
- Where do router loopbacks and point-to-point links go?
- How does the plan help firewall rules and reverse DNS?
- Would a /56 have been enough for this company?
From the lesson IPv6 addresses and prefixes
Model answer, Pro. Model answers open with any pass; prices are in the notice on this page.Opening the model answers with your pass…
Model answers open with any MySmartCoPilot pass.
- Pro pass · 1 week₹79$2.99
- 30 days₹179$5.99
- 1 year₹1,699$45
One payment; a pass never renews. The price shown is the total you pay: no fees or charges are added at checkout.
Passes can’t be bought right now, so the model answers can’t be opened at the moment. If you have a pass, enter your licence key.
It also opens every other in-depth part in Learn and every Pro tool. Sales are final, except where the law gives you a right to withdraw, for example in the EU and the UK (refund policy).
In the answer:
- Model answer
- Follow-up answers
- Common mistakes
- Rubric
- Variants
- about 3 minutes
-
Mid to senior
An analytics job counts unique visitors by client IP address. For the same traffic it reports about four times as many IPv6 visitors as the IPv4 numbers suggest. What is going on, and how would you count?
- What it tests
- Canonical text forms, temporary addresses and how often they change, NAT on the IPv4 side, and choosing an aggregation such as the /64 that matches what you want to count.
- First step
- Separate two effects. First, check whether one address appears in several spellings, such as upper and lower case or different compressions, and normalise by parsing it. Then count how many addresses each /64 shows per day: devices create new temporary addresses at least daily, while on IPv4 whole households share one address.
- Follow-ups
-
- Why does IPv4 undercount at the same time?
- Is a /64 a good unit on mobile networks?
- How should the database store addresses?
- A dual stack server logs some IPv4 clients as ::ffff:192.0.2.10. Does that matter?
From the lesson IPv6 addresses and prefixes
Model answer, Pro.In the answer:
- Model answer
- Follow-up answers
- Common mistakes
- Rubric
- Variants
- about 3 minutes
All Computer Networks interview questions · The Computer Networks track