A layer-4 firewall (a device that can look at all protocol

A layer-4 firewall (a device that can look at all protocol headers up to the transport layer) cannot

1. block entire HTTP traffic during 9 : 00 PM and 5 : 00 AM
2. block all ICMP traffic
3. stop incoming traffic from a specific IP address but allow outgoing traffic to the same IP address
4. block TCP traffic from a specific user on a multi-user system during 9 : 00 PM and 5 : 00 AM

Since, it is a layer 4 firewall, it cannot block application layer protocol like HTTP.