Analyzing the costs (and benefits) of DNS, DoT, and DoH for the modern web.

We measure the effect of DoH and DoT on name resolution performance and content delivery. We find that although DoH and DoT response times can be higher than for conventional DNS (Do53), DoT performs better than DoH and Do53 in terms of page load times. However, when network conditions degrade, webpages load quickest with Do53, and up to one second faster compared to DoH. Furthermore, in a substantial amount of cases, a webpage may not load at all with DoH, while it loads successfully with DoT and Do53. Our in-depth analysis reveals various opportunities to readily improve DNS performance, for example through opportunistic partial responses and wire format caching.