I noticed that sometimes (not everytime) I had "Server Not Found" error on some of my website. Since i have a DNS server at home i thought it was probably related to that so I opened Wireshark to see what was happening. to better understand I have 2 dns records server.lan that point to 192.168.1.61 and *.mydomain.com that points to server.lan with a CNAME. In wireshark i saw that generally firefox does A and HTTPS(TYPE 65) queries but sometimes it only does HTTPS. In case of a Type 65 query my dns server only answers with the CNAME so server.lan The issue is that Firefox doesnt try to resolve the CNAME. When firefox do both A and Type65 it seems to work probably because it takes the A answer wich contains both cname and the IP of the CNAME but when it doesn't do both it just stop after the HTTPS one without trying to resolve the CNAME. Google chrome seems to always do Both A and Type 65 query.