Bandwidth versus latency

The correct answer: B. High latency (round-trip delay)

✅ Why this answer

The two decisive clues: the distance is great, and the link is not congested after its speed was raised. So the problem is not the amount of data, but the round-trip time of each request (latency).

An application that sends many small requests waits for the reply to each one before sending the next, so the effect of the delay multiplies however fast the link is.

❌ Why the other options are wrong

• (A) Bandwidth: it rose tenfold and utilization is low, so it is not the bottleneck.
• (C) Storage: a lack of server space causes failures or slowness for all users, not for the remote clinic alone.
• (D) The number of licenses: determines who can sign in, and does not cause slow responses.

💡 Key concept

• Bandwidth: how much data passes per second; like the number of lanes on a road.
• Latency: how long a single trip takes; like the length of the road.

Adding lanes does not make the road shorter. The solutions for delay: a web application or a virtual desktop running close to the server, a local server, or reducing the number of round trips in the application.

🔗 Related facts and questions

• The four measures of network performance: bandwidth (capacity: how much passes per second), latency (the time of a trip, measured in milliseconds), jitter (variation in arrival time from one packet to the next), and packet loss (packets lost on the way). Add throughput: what actually gets through, usually less than the nominal capacity of the link.
• Which measure matters to which application? Moving large radiology images (PACS) needs capacity. An application that exchanges many small requests is affected by latency. Voice and video in telehealth are affected by jitter and packet loss.
  Practice question: loading a full CT study takes minutes, and the link is 95% utilized. Which measure is involved? → Bandwidth.
• Quality of service (QoS): network settings that give priority to time-sensitive traffic (voice, video, clinical applications) over traffic that can wait (backups, updates).
  Practice question: a backup has to run during the day, and telehealth calls break up while it runs. Which network setting fixes this without buying a new line? → QoS.
• Solutions for distance: a virtual desktop (VDI), so the application runs close to the server and only the screen image travels; a web application whose logic runs on the server, so the many small exchanges with the database stay inside the data center; a local server at the remote site; or WAN optimization appliances.
• Web-based versus client-server applications: "Web-based applications versus client-server" (in the full bank).
• Connecting remote clinics to the hospital network: a related question in the full bank.
• Practice question: on a telehealth video call the sound cuts out and the picture freezes, although the line is fast and lightly used. Which two measures are checked first? → Jitter and packet loss.