DNS-based server redirecting has been realized as the most popular way to deploy CDNs. However, with the increasing use of remote DNS, DNS-based CDNs faces a great challenge in performance degradation. To address this challenging issue, encouraging progress has been made from both industry and research communities. In this article, the state-of-art solutions for the remote DNS problem are discussed at first. Next, the privacy concerns about DNS-based CDN, including client location as well as redirection privacy, are identified and a representative solution is summarized. At last, comparisons for prior work under the different measures are conducted. We believe that this survey will shed lights on the application of DNS-based CDNs and it is expected to provide design guidelines to the CDN service providers.