The use of the Azure firewall to limit the egress traffic from an AKS cluster is not very useful. To permit the survive of the cluster, MSFT declares to open to a particular FQDN some TCP Ports like 22, 9000 etc but we are not able to allow on Network Rules section the TCP ports only versus a specific FQDN. The FQDN filtering is allowed only in the application rule section but in that case we have only https, http, sql protocols/ports.