F5 F5CAB1 Exam Dumps - Actual Questions Answers

Comprehensive and Detailed Explanation From BIG-IP Administration — Install, Initial Configuration, and Upgrade:

BIG-IP Self IP addresses have an associated Port Lockdown feature that governs which protocols and services are permitted to communicate directly with that Self IP. By default, Self IPs may allow broader access than desired, making Port Lockdown a critical hardening control.

The Allow Custom option under Port Lockdown is the precise mechanism for administrators who need granular, port-specific filtering. When selected, only the explicitly listed TCP/UDP ports are permitted — all others, including port 443 (HTTPS), are implicitly denied. This satisfies the requirement of blocking 443 specifically while preserving access on other required ports.

The remaining options are incorrect for this scenario:

Option A references SSH access control under System » Platform, which governs management-plane SSH — not Self IP service filtering.

Option B disables the entire Self IP, removing all traffic handling, which is operationally disruptive.

Option D — Allow None — blocks all traffic to the Self IP, not selectively port 443.

The Allow Custom approach provides the surgical precision required: administrators enumerate permitted ports, and everything outside that list — including 443 — is dropped.

Reference Topics: Self IP Port Lockdown, Network Security Hardening, Self IP Configuration — BIG-IP Administration Study Guide.

The screenshot shown is from the User Administration section of the BIG-IP GUI.

This section controls:

Root and Admin passwords

SSH Access

SSH IP Allow settings

However, it does not contain any controls for restricting access to the WebUI (TMUI) .

BIG-IP does not provide TMUI access restrictions from this part of the GUI.

Access to the web-based Configuration Utility is controlled by the httpd allow list , configured through TMSH:

tmsh modify /sys httpd allow { < IP/subnet > }

This setting is not displayed in the User Administration panel, and in many BIG-IP versions, the httpd allow list is only configurable from the CLI , not the GUI.

Therefore, the administrator cannot find the setting in the screen shown because:

TMUI access restriction is not located in this GUI section

It must be configured using tmsh under /sys httpd allow

This is why Option A is correct.

When a TMOS ISO file is transferred to /shared/images/ , the BIG-IP automatically performs a validation step:

Checksum Verification

Before the image becomes visible in the GUI, the system verifies the internal checksum embedded inside the ISO.

This ensures:

The file was fully transferred

The image is not corrupted

It matches the official F5 release signature

Only after passing this verification does the GUI display the ISO under “Available Images.”

Why the other options are incorrect:

A. Reboot into a new partition

No reboot occurs simply from uploading an image.

C. Copying into /var/local/images/

This directory is not used for ISO storage.

All valid images remain in /shared/images/ .

Thus, the correct system action is checksum verification .