100-150 Question 262
Single answerA network administrator is tasked with securing a company’s network using a firewall. The firewall is configured to allow inbound traffic only on TCP port 443 for secure web applications and block all other incoming traffic. How does the firewall enforce this rule?
- A
It analyzes the IP address of every packet and blocks packets not matching the allowed IP addresses.
- B
It inspects the packet headers to permit traffic on TCP port 443 and denies traffic on other ports.
- C
It monitors outgoing traffic and automatically allows only responses to that traffic.
- D
It encrypts all incoming traffic to determine whether it matches the allowed criteria.
Show answer and explanation
Correct answer: B
Explanation
Firewalls operate by inspecting packet headers to determine whether the traffic matches predefined rules, such as allowing TCP traffic on a specific port. In this scenario, the firewall enforces the rule by permitting traffic only on TCP port 443 for secure web applications, while blocking all other incoming traffic. This ensures network security by filtering traffic based on ports and protocols.
- A. Incorrect.
Firewalls primarily filter traffic based on rules such as ports, protocols, and IP addresses, but this option incorrectly suggests that the firewall only blocks packets based on IP address, which is not specific to the scenario.
- B. Correct.
This is correct because firewalls inspect packet headers to identify information such as port numbers, and in this case, allow traffic on TCP port 443 while blocking others.
- C. Incorrect.
This describes a behavior more specific to stateful firewalls, which allow responses to outgoing traffic. However, the question specifies inbound traffic filtering, which is not addressed here.
- D. Incorrect.
Firewalls do not encrypt traffic to filter it. Encryption is a separate process unrelated to the described operation of a firewall.