DNS plays a critical role in the performance of smartdevices within cellular networks. Besides name resolution, DNS is commonly relied upon for directing users to nearby content caches for better performance. In light of this, it is surprising how little is known about the structure of cellular DNS and its effectiveness as a client localization method. In this paper we take a close look at cellular network DNS and uncover several features of cellular DNS, such as cellular network opaqueness and client to resolver inconsistency, that make it unsuitable for client localization in modern cellular networks. We study these issues in two leading mobile network markets - US and South Korea - using a collection of over 340 volunteer devices to probe the DNS infrastructure of each client's cellular provider. We show the extent of the problem with regards to replica selection and compare its localization performance against public DNS alternatives. As a testament to cellular DNS's poor localization, we find surprisingly that public DNS can render equal or better replica performance over 75% of the time.
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