100-150 Question 261
Select 4You are troubleshooting a network issue where internal users cannot access a specific external website. Upon checking the firewall logs, you notice that traffic to the website's IP address is being blocked. Which of the following could be a reason for this behavior?
- A
The firewall is configured with an access control list (ACL) that explicitly denies traffic to the website's IP address.
- B
The firewall uses stateful inspection and is blocking the return traffic because the initial request was not detected.
- C
The firewall is configured to block traffic to websites with unverified SSL certificates.
- D
The website's IP address matches an entry in the firewall's blacklist.
- E
The firewall is configured to block all outgoing traffic by default and requires explicit rules to allow specific connections.
Show answer and explanation
Correct answers: A, B, D, E
Explanation
Firewalls operate by enforcing rules that filter traffic based on parameters such as IP addresses, protocols, and connection states. In this scenario, traffic to the external website may be blocked due to an ACL, stateful inspection rules, blacklist entries, or a default deny policy. Understanding how firewalls filter traffic helps in identifying and resolving such issues.
- A. Correct.
Correct: If an ACL explicitly denies traffic to the website's IP address, the firewall will block the traffic regardless of other factors.
- B. Correct.
Correct: Firewalls with stateful inspection track connections and can block return traffic if the initial outbound request was not properly tracked.
- C. Incorrect.
Incorrect: Firewalls generally do not block websites based solely on SSL certificate verification; this is typically handled by endpoint browsers or proxy servers.
- D. Correct.
Correct: If the website's IP address is on a blacklist configured on the firewall, traffic to that IP will be blocked.
- E. Correct.
Correct: Firewalls often use a default deny policy for outbound traffic, requiring explicit rules to permit specific traffic flows.