The scenario describes an e-commerce website with performance degradation during "random periods," indicating unpredictable traffic spikes. Automatic elasticity is a fundamental cloud computing characteristic designed specifically for this use case. It allows the system to automatically scale resources (e.g., compute instances) up or down based on real-time demand, monitored through metrics like CPU utilization or network traffic. This ensures that the website has sufficient resources to maintain performance during unexpected surges and scales down to reduce costs when the demand subsides. This dynamic and automated approach is the most effective and efficient way to manage variable workloads.

A. Migrating to a dedicated host: This provides a fixed amount of resources. It does not dynamically scale to meet random demand and can lead to either under-provisioning or costly over-provisioning.

B. Purchasing additional servers: This is a static, capital-intensive solution. It lacks the agility to respond to real-time, random fluctuations in traffic and is not a typical cloud approach.

C. Scheduling resource allocation: This method is only effective for predictable, cyclical traffic patterns (e.g., daily or weekly peaks), not for the "random periods" mentioned in the question.

1. Mell

P.

& Grance

T. (2011). The NIST Definition of Cloud Computing (Special Publication 800-145). National Institute of Standards and Technology. On page 2

under "Essential Characteristics

" it defines Rapid elasticity: "Capabilities can be elastically provisioned and released

in some cases automatically

to scale rapidly outward and inward commensurate with demand."

2. Armbrust

M.

Fox

A.

Griffith

R.

Joseph

A. D.

Katz

R.

Konwinski

A.

... & Zaharia

M. (2010). A view of cloud computing. Communications of the ACM

53(4)

50-58. In Section 3.1

"Elasticity and the Illusion of Infinite Resources

" the UC Berkeley authors state

"Cloud Computing gives the illusion of infinite computing resources available on demand... This elasticity of resources

without paying a premium for large scale

is unprecedented in the history of IT." This directly addresses the need to handle variable demand effectively. DOI: https://doi.org/10.1145/1721654.1721672

3. Vaquero

L. M.

Rodero-Merino

L.

Caceres

J.

& Lindner

M. (2008). A break in the clouds: towards a cloud definition. ACM SIGCOMM Computer Communication Review

39(1)

50-55. In Section 3

"A Proposed Definition

" the paper highlights elasticity as a key property

stating that it "allows for the dynamic reconfiguration of the infrastructure according to the service's needs." This supports the use of elasticity for managing fluctuating performance requirements. DOI: https://doi.org/10.1145/1496091.1496100