IPv6 Monitoring

As of February 2011, IANA allocated the last large block of IPv4 addresses, and the RIRs are expected to rapidly follow suit with some already having depleted their allocated blocks (see http://www.potaroo.net/tools/ipv4 for regularly updated estimates). As a result, migrating the Internet to IPv6 is becoming increasingly important. This migration is, however, largely dependent on ensuring that the current IPv4 Internet, and in particular its content, becomes accessible over IPv6. Tracking the extent to which this is happening is the main purpose of this effort.

This tracking is performed by a monitoring client that queries the Domain Name System (DNS) for IPv4 and IPv6 addresses (A and quad-A records) for a number of known sites. The list of sites queried includes the top one million (1M) web sites according to the ranking maintained by Alexa, and possibly additional sites beyond the top 1M.

Content is deemed IPv6 accessible if DNS returns a quad-A record for the site. Sites identified as being both IPv4 and IPv6 accessible are then queried for content, and deemed IPv4 and IPv6 reachable if the same content can be retrieved over both. The relative performance of content retrieval over IPv4 and IPv6 is then compared based on a succession of queries for sites that offer the same content in IPv6 and IPv4.

In order to provide a comprehensive perspective on the level of IPv6 adoption across the Internet, the monitoring software has been deployed at multiple locations (a paper documenting initial findings is available here), with the goal of ultimately making the information gathered across locations publicly available to facilitate research and evaluation by others. The data available on this site is obtained from the monitoring performed at Penn since around July 2009.

Note: Sites are deemed to offer the same content over IPv4 and IPv6 if they return pages of approximately the same size.

The data gathered by the monitoring client is displayed in a number of figures as described below. Additional details are provided in the page associated with each figure. Figures can be scaled by selecting a corresponding area in the figure, and additional information can be obtained about individual data points by positioning the mouse cursor on top of them.

Want to Become Involved?

If you are interested in becoming involved in this monitoring effort, send an email to Prof. R. Guerin at the University of Pennsylvania. The software is made available under an Open BSD copyright agreement. However, there is an implicit understanding that sites which receive a copy of the monitoring software will be willing to make their results available to the common repository maintained by the University of Pennsylvania. In particular, this implies the agreement not to disable the upload functionality of the client, which is responsible for transferring monitoring results to the Penn repository after each round of measurement.


Prof. Roch Guerin started this project in 2009, and the core of the Monitoring Software was written by Pei Yan (then a Master's student at UPenn) in the same year. From 2009 to 2015, Mehdi Nikkhah contributed to this project (as a part of his Ph.D. studies) under the supervision of Prof. Roch Guerin, by modifying, upgrading, and installing the software on various sites around the world, in addition to collecting and analyzing the data from those locations. The vantage points which host the Monitoring Software include UPenn (Philadelphia, PA), Comcast HQ (Philadelphia, PA), Comcast (Denver, Colorado), UPCB (Netherlands), Loughborough University (England), and Tsinghua University (China). Below is the list of related publications stemmed from this project.

The project started as a joint project between the University of Pennsylvania and Comcast, and initially was partially supported by a grant from Comcast to the University of Pennsylvania. It has subsequently been supported by NSF grants CNS-1116039 and CNS-1224514.