You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: A Survey on Content Placement Algorithms for Cloud-Based Content Delivery Networks 
Chapter Title:  A. CLOUD MODEL 1) OPERATIONAL COST VS. QoS 
1. Abstract of Cited Paper (BIB001):  YouTube is the most popular service in today's Internet. Google relies on its massive content delivery network (CDN) to push YouTube videos as close as possible to the end-users, both to improve their watching experience as well as to reduce the load on the core of the network, using dynamic server selection strategies. However, we show that such a dynamic approach can actually have negative effects on the end-user quality of experience (QoE). Through the comprehensive analysis of one month of YouTube flow traces collected at the network of a large European ISP, we report a real case study in which YouTube QoE-relevant degradation affecting a large number of users occurs as a result of Google's server selection strategies. We present an iterative and structured process to detect, characterize, and diagnose QoE-relevant anomalies in CDN distributed services such as YouTube. The overall process uses statistical analysis methodologies to unveil the root causes behind automatically detected problems linked to the dynamics of CDNs' server selection strategies.

Literature Review:
The dynamic and short-term resource provisioning in the cloud is also the underlying contributor to operational cost. There is a direct tradeoff between operational cost and QoS that a CP strategy offers. It is imperative to scrutinize and quantify the tradeoff or the cost of striking a balance between operational cost and QoS. For example, Jin et al. BIB001 have identified a novel relationship between the number of replicas of content and the mean hop distance between end-users and content. Critical research objectives include (i) the quantification of the effect of the number of replicas on QoS for end-users, (ii) analyzing the cost of offering hard and/or soft QoS, (iii) the effect of overhead pertaining to leasing and initializing resources in the cloud on QoS for end-users, with respect to delay. However, there are some key performance indicators and metrics for measuring and defining the subjective QoE BIB002 . The challenge lies in scrutinizing the impact of QoE parameters over QoS metrics for CP in CCDNs.