Also order certificates, so we have: * intermediate * root * alternative root, if any Let's add 'ISRG Root X1' for 'E1' as there will be a valid cross-signed chain 'E1' -> 'ISRG Root X2' -> 'ISRG Root X1'.
This is used by DNS over HTTPS services: https://cloudflare-dns.com/dns-query https://dns9.quad9.net/dns-query (secured) https://dns10.quad9.net/dns-query (unsecured) https://github.com/curl/curl/wiki/DNS-over-HTTPS