We present a large-scale measurement of clusters of hosts sharing the same local DNS servers. We analyze properties of these "LDNS clusters" from the perspective of content delivery networks, which commonly use DNS for load distribution. We found that not only LDNS clusters differ widely in terms of their size and geographical compactness but that the largest clusters are actually extremely compact. This suggests potential benefits of a load distribution strategy with nuanced treatment of different LDNS clusters based on the combination of their size and compactness. We further observed interesting variations in LDNS setups including a wide use of "LDNS pools" (which as we explain in the paper are different from setups where end-hosts simply utilize multiple resolvers).
['Hussein A. Alzoubi', 'Michael Rabinovich', 'Oliver Spatscheck']
The anatomy of LDNS clusters: findings and implications for web content delivery