Which symbol represents a firewall in network diagrams?

Which symbol represents a firewall in network diagrams?

• A. Shield icon
• B. Padlock icon
• C. Brick wall symbol
• D. Lightning bolt

Answer: (C)

In network diagrams, the firewall’s job is to act as a barrier between trusted and untrusted networks, filtering traffic to enforce security policies. The brick wall symbol visually embodies that barrier role—it's a clear, intuitive representation of something standing in the way of unwanted access while still allowing controlled traffic. That’s why it’s the best visual cue for a firewall. The other symbols don’t fit as well. A shield suggests general protection but isn’t specific to the barrier function of a firewall. A padlock points to encryption or securing a channel, not the device that filters traffic. A lightning bolt usually indicates power, speed, or alerts rather than a firewall.

In network diagrams, the firewall’s job is to act as a barrier between trusted and untrusted networks, filtering traffic to enforce security policies. The brick wall symbol visually embodies that barrier role—it's a clear, intuitive representation of something standing in the way of unwanted access while still allowing controlled traffic. That’s why it’s the best visual cue for a firewall.

The other symbols don’t fit as well. A shield suggests general protection but isn’t specific to the barrier function of a firewall. A padlock points to encryption or securing a channel, not the device that filters traffic. A lightning bolt usually indicates power, speed, or alerts rather than a firewall.