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Center for Applied Internet Data Analysis > research : dns : influence-map
Influence Map of DNS Root Anycast Servers
This visualization shows the geographic distribution of DNS clients for anycast instances. We provide two world maps for each root, with individual anycast servers placed on the map at the "center of influence" of its observed clients. Wedges fanning out from each server indicate the direction, distance, and number of clients observed within the bounding angle of the wedge.

Influence Map

This visualization focuses on the geographic location of clients for each anycast instance. We represent each DNS root server with a pair of maps, both of which project the world as viewed from the North Pole. We locate the server nodes (anycast instances) at their "center of influence." To determine this location, we consider each of a server's clients as a point with mass 1, then we use those client locations to compute the centroid. Thus, anycast root nodes that serve a primarily local clientele remain closer to their actual geographic locations while nodes that tend to serve a more geographically distant client set get displaced on our maps toward the regions where they have the most clients. In both maps, the location of each node reflects the centroid (center of influence) of its clients geographic locations not the actual geographic location of the server.

Displacement Map (smaller map)

For servers whose actual location and centroid differ visually, the smaller maps show these instances' geographic displacement using a ray (gray line) beginning at the server's actual geographic location and ending with the node located at the centroid. We place the label for each server on the edge of the "drift" line, close to the server's actual projected location.

Location Map (larger map)

The larger map uses wedges to show the relationship between each instance and its clients. The larger map plots each server as a circle surrounded by a group of wedges. The wedges show the relationship between each instance and its clients. Each wedge represents the number and average distance of clients from the instance's centroid in the direction toward which the wedge points. Each wedge color represents the number of clients and its length represents their average distance. The size of the circle represents the server's total number of clients.

Influence Maps by year

January 9-10, 2007

2007 Influence Map (.png) (.eps)

2007 Poster (.png) (.ps versions: 18x12 36x24)

January 10-11, 2006

2006 Influence Map (.png) (.eps )

2006 Poster (.png) (.ps version: 18x12)
  Last Modified: Tue Jul-17-2007 10:15:51 PDT
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