When an outgoing request is made on a port number greater than 1023, this type of firewall creates an ACL to allow the incoming reply on that port to pass:

The correct answer is C. Dynamic packet filtering. Dynamic packet filtering firewalls (also called stateful packet inspection firewalls) are intelligent enough to track outbound connections and automatically create temporary Access Control List (ACL) entries to permit the corresponding inbound reply traffic. When a client…

Submitted by lukas.cz· Apr 18, 2026Access Controls

Question

Options

Apacket filtering
BCIrcuit level proxy
CDynamic packet filtering
DApplication level proxy

How the community answered

(41 responses)

A
5% (2)
B
2% (1)
C
90% (37)
D
2% (1)

Explanation

Dynamic packet filtering firewalls (also called stateful packet inspection firewalls) are intelligent enough to track outbound connections and automatically create temporary Access Control List (ACL) entries to permit the corresponding inbound reply traffic. When a client initiates an outgoing request using an ephemeral port (ports 1024–65535), the dynamic packet filter records this in a state table and opens a temporary 'hole' for the reply. Static packet filtering cannot do this - it requires pre-configured static rules. Circuit-level and application-level proxies work differently by acting as intermediaries rather than dynamically modifying ACLs.

Topics

#Firewall types#Stateful inspection#Network access control#Ephemeral ports

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