IPA IP 2020 Question 78
A question IPA Japan published in 令和2年度 10月 ITパスポート試験 公開問題 問78, translated into English. ITPEC is based on the same exams.
VPNs that use TCP/IP as the communication protocol include an Internet VPN, which uses the Internet, and an IP-VPN, which uses a telecommunications carrier's own network. Which of the following cannot be done with an Internet VPN but can be done with an IP-VPN?
Explanation
Guaranteeing communication quality such as bandwidth — possible on a carrier's managed closed network, not on the shared Internet.
An Internet VPN builds an encrypted tunnel over the Internet. The Internet is a best-effort network shared by everyone: bandwidth and delay change with congestion, and no one can guarantee them. An IP-VPN runs on the telecommunications carrier's own closed IP network, which the carrier manages end to end, so it can offer guaranteed bandwidth and other quality levels by contract.
Answer (b)
Why not others:
- •(a) — voice calls using IP telephony also run over an Internet VPN; only their quality may vary
- •(c) — preventing eavesdropping and tampering is what both kinds of VPN do; an Internet VPN does it by encrypting with IPsec or TLS
- •(d) — videos can be distributed over either network
Key rule: Internet VPN = low cost, best effort; IP-VPN = a carrier's closed network that can guarantee quality such as bandwidth.
Networks · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.