AWS Certified SysOps Administrator – Associate (legacy) — Question 218

A customer has a web application that uses cookie Based sessions to track logged in users. It is deployed on AWS using ELB and Auto Scaling. The customer observes that when load increases. Auto Scaling launches new Instances but the load on the easting Instances does not decrease, causing all existing users have a sluggish experience.
Which two answer choices independently describe a behavior that could be the cause of the sluggish user experience? (Choose two.)

Answer options

• A. ELB's normal behavior sends requests from the same user to the same backend instance
• B. ELB's behavior when sticky sessions are enabled causes ELB to send requests in the same session to the same backend instance
• C. A faulty browser is not honoring the TTL of the ELB DNS name
• D. The web application uses long polling such as comet or websockets. Thereby keeping a connection open to a web server tor a long time

Correct answer: B, D

Explanation

Option B is correct because when sticky sessions are enabled, ELB will route all requests from a particular session to the same instance, causing load on that instance to remain high. Option D is also correct as long polling or websockets can keep connections open for long durations, exacerbating the load issue. Options A and C do not independently contribute to the sluggish experience in the same way as B and D.