In his regular monthly spot on PING, APNIC’s Chief Scientist Geoff Huston re-visits the question of DNS Extensions, in particular the EDNS0 option signalling maximum UDP packet size accepted, and it’s effect in the modern DNS. Through the APNIC Labs measurement system Geoff has visibility of the success rate for DNS events where EDNS0 signalling triggers DNS “truncation” and the consequent re-query in TCP as well as the impact of UDP fragmentation even inside the agreed limit, as well as the ability to handle the UDP packet sizes proffered in the settings. Read more about EDNS0 and UDP on the APNIC Blog and at APNIC Labs Revisiting DNS and UDP truncation (Geoff Huston, APNIC Blog July 2024) DNS TCP Requery failure rate (APNIC Labs)