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:  D. OTHER IMPLICATIONS 1) REQUEST REDIRECTION 
1. Abstract of Cited Paper (BIB001):  Geographically distributed cloud platforms enable an attractive approach to large-scale content delivery. Storage at various sites can be dynamically acquired from (and released back to) the cloud ...

Literature Review:
Another research challenge is the effectiveness and cost analysis of a smarter CCDN request redirection scheme, which greatly impacts QoE BIB001 . Request redirection is aware of the surrogate servers and their content and redirects enduser requests based on load-balancing, QoS or network health metrics. This scheme can utilize neural network or reinforcement learning techniques to build a surrogate-content relationship table such that the redirection is simply a look up in the table. However, the exchange of information between the redirector and the surrogate servers incurs bandwidth and storage costs at the redirector. It is interesting to scrutinize the economic benefits of this redirector and the latency and responsiveness of this scheme. It remains a challenge to evaluate CP algorithms efficiency with BIB002 and without request redirection techniques.