Date for your diary: October 11th, 2022 OARC AGM 2022. Click on the link to register your attendance.
Sep 28 – 29, 2020
UTC timezone

A Look at the ECS Behavior of DNS Resolvers

Sep 28, 2020, 2:30 PM
Standard Presentation Online Workshop OARC 33 Day 1


Dr Kyle Schomp (Akamai)


Content delivery networks (CDNs) commonly use DNS to map end-users to the best edge servers. A recently proposed EDNS0-Client-Subnet (ECS) extension allows recursive resolvers to include end-user subnet information in DNS queries, so that authoritative DNS servers, especially those belonging to CDNs, could use this information to improve user mapping. In this paper, we study the ECS behavior of ECS-enabled recursive resolvers from the perspectives of the opposite sides of a DNS interaction, the authoritative DNS servers of a major CDN and a busy DNS resolution service. We find a range of erroneous (i.e., deviating from the protocol specification) and detrimental (even if compliant) behaviors that may unnecessarily erode client privacy, reduce the effectiveness of DNS caching, diminish ECS benefits, and in some cases turn ECS from facilitator into an obstacle to authoritative DNS servers’ ability to optimize user-to-edge-server mappings.

This talk will summarize the key findings of the study, as first published in the Internet Measurement Conference, 2019.

Postponement (Please leave blank)

  • [Jan] September date works for the speaker.

  • In order of preference:
    present at the postponed OARC 33, currently planned for September 26th and 27th later this year in Milan?
    do a remote presentation for a virtual OARC 33 in case a physical workshop is still not possible?
    do a remote presentation for a virtual OARC 34 in case a physical workshop is still not possible?
    do a remote presentation for virtual mini-OARC or other OARC activity at any time?

Talk Duration 20 minutes

Primary authors

Dr Rami Al-Dalky (Case Western Reserve University) Dr Michael Rabinovich (Case Western Reserve University) Dr Kyle Schomp (Akamai)

Presentation materials