Why is it needed to connect to cloudfront.net while pulling the images from quay.io ?

Issue

• Just wondering why it is needed a connection to "d3uo42mtx6z2cr.cloudfront.net" when trying to pull etcd from quay.io.

$ strace -s 128 skopeo --insecure-policy copy docker://quay.io/coreos/etcd:v3.3.18 dir:etcd > strace.skopeo.txt 2>&1 

$ grep cloudfront strace.skopeo.txt
write(3, "CONNECT d3uo42mtx6z2cr.cloudfront.net:443 HTTP/1.1\r\nHost: d3uo42mtx6z2cr.cloudfront.net:443\r\nUser-Agent: Go-http-client/1.1\r\n\r\n", 127) = 127