F5CAB1 BIG-IP Administration Install, Initial Configuration, and Upgrade Questions and Answers

From the exhibit, the administrator performs the following actions:

Displays the current SSH allow configuration:

tmsh list sys sshd allow

allow { ALL }

Replaces the existing SSH allow list with a specific subnet:

tmsh modify sys sshd allow replace-all-with { 10.0.0.0/24 }

Confirms the updated configuration:

tmsh list sys sshd allow

allow { 10.0.0.0/24 }

This configuration restricts SSH access to only hosts that fall within the 10.0.0.0/24 network.

Evaluation of the options

A. 10.0.0.100

This address is within the 10.0.0.0/24 subnet and is a valid host address, so SSH access is permitted.

B. 10.0.0.254

This address is also within the 10.0.0.0/24 subnet and is a valid host address, so SSH access is permitted.

C. 10.0.0.256

This is not a valid IP address because an IPv4 octet cannot exceed 255.

D. 100.0.1.10

This address is outside the configured 10.0.0.0/24 subnet and will not be allowed.

E. 100.0.0.10

This address is also outside the configured subnet and will not be allowed.

Port Lockdown controls which ports and protocols a Self IP will respond to.

However, certain traffic types bypass Port Lockdown for BIG-IP functionality and routing integrity.

The three types that are NOT affected by Port Lockdown are:

1. Defined Virtual Server Traffic

Traffic destined to a Self IP that matches a configured virtual server is always accepted by the BIG-IP, regardless of Port Lockdown settings.

This ensures that traffic processing does not break when administrators restrict Self-IP ports.

2. ICMP (Internet Control Message Protocol)

ICMP (such as ping, traceroute responses, etc.) always passes through a Self IP even when Port Lockdown is set to:

Allow Default

Allow None

Allow Custom

F5 allows ICMP for reachability and diagnostic purposes independent of Port Lockdown rules.

3. Centralized Management Infrastructure (CMI)

CMI includes the internal HA services used for:

Device Trust

ConfigSync

Failover

Mirroring

These essential HA communications bypass Port Lockdown to prevent accidental cluster failure.

The well-known port for this traffic is TCP 4353 , which is always permitted.

Why the other options are incorrect:

Option A: SSH is restricted by Port Lockdown unless explicitly allowed.

Option B: Same issue — SSH does not bypass Port Lockdown.

Only Defined VS Traffic , ICMP , and CMI bypass Port Lockdown.

Self-IPs include a security feature called Port Lockdown , which restricts which services respond on that Self-IP.

By default, Self-IPs block management access (SSH and HTTPS/TMUI), meaning an administrator cannot manage the device through in-band Self-IPs unless explicitly allowed.

Allow Mgmt / Allow Management

These settings enable only the management services required for administrative access, specifically:

SSH (22)

HTTPS/TMUI (443)

These options allow secure administration without opening unnecessary ports.

Why these are correct:

They provide only the essential access for management.

They follow F5 security best practices when using in-band admin access.

They do not expose all services, reducing the attack surface.

Why the other options are incorrect:

A. Allow Default

This allows only a minimal set of system-required ports (e.g., failover, config sync), not SSH or HTTPS.

Administrator access would still fail.

B. Allow All

Opens all ports on the Self-IP, which is not secure .

Exposes services that should remain restricted.

Therefore, Allow Mgmt / Allow Management are the correct choices.

Access to the BIG-IP Configuration Utility (TMUI) is controlled through the /sys httpd allow list.

This list defines which IP addresses or subnets are allowed to connect to the management web interface.

To allow two new subnets— 172.28.31.0/24 and 172.28.65.0/24 —the administrator must add both subnets to the existing list without removing current entries.

In tmsh, subnet entries must be specified in network/netmask format , for example:

172.28.31.0/255.255.255.0

The correct tmsh command to append these networks is:

modify /sys httpd allow add { 172.28.31.0/255.255.255.0 172.28.65.0/255.255.255.0 }

Why the other options are incorrect:

Option B:

IPs are listed without masks, which is invalid for subnet-based access control.

The system requires network/netmask format.

Option C:

The command uses permit instead of allow, which is not a valid attribute of /sys httpd.

The correct keyword must be allow .

Thus, only Option A correctly adds both permitted subnets in the proper tmsh format.

BIG-IP module provisioning determines how CPU, memory, and disk resources are allocated to each licensed module. F5 defines a specific set of supported provisioning levels.

Valid provisioning (resource allocation) settings

Nominal

Allocates a standard, balanced amount of system resources to a module.

Intended for typical production deployments where multiple modules may be provisioned at the same time.

Dedicated

Allocates all available system resources to a single module.

Used when the BIG-IP device is dedicated to running only one module (for example, ASM-only or APM-only deployments).

No other modules can be provisioned when one is set to Dedicated.

These two options are valid and supported provisioning levels.

Why the other options are incorrect

Maximum

This is not a valid BIG-IP provisioning level.

BIG-IP does not use “Maximum” as a resource allocation setting.

Limited

This is also not a supported provisioning level.

BIG-IP uses levels such as None, Minimal, Nominal, and Dedicated (module-dependent), not Limited.

BIG-IP allocates CPU and memory resources based on module provisioning levels.

To view how much CPU a module is assigned, administrators must check provisioning information from:

C. GUI — System » Resource Provisioning

This page visually displays CPU allocation via color-coded bars.

Hovering over the CPU bar shows:

CPU usage percent per module

Which modules share CPU cycles

The system’s total resource allocation

This is the primary GUI method.

D. tmsh show /sys provision

This command displays detailed module provisioning information including:

Provisioned modules

Their provisioning level

CPU and memory allocation data

It is the authoritative CLI method for resource provisioning status.

Why the other options are incorrect:

A. top

Shows real-time process usage, not provisioned CPU allocation.

B. tmsh show /sys cpu

Displays CPU runtime utilization, not per-module provisioning.

E. Statistics Dashboard

Only shows traffic / system runtime metrics, not provisioning resource allocations.

Therefore, C and D are correct.

To understand:

Which modules are licensed

Which modules are provisioned

The resource requirements (CPU / RAM) of each module

The administrator uses:

System » Resource Provisioning

This page displays:

All modules present in the license

Whether they are enabled or disabled

Required memory to activate each module

CPU and disk allocation information

Provisioning level options (None / Minimal / Nominal / Dedicated)

This is the exact location where BIG-IP administrators evaluate module capacity before enabling or purchasing licensing upgrades.

Why the other options are incorrect:

A. Configuration » OVSDB

Used for network virtualization integrations, not licenses or modules.

B. Software Management

Used for software image installation, not licensing.

C. Configuration » Device

Displays hostname, failover settings, device properties — not module resource requirements.

Thus, module licensing and memory requirement data are found under Resource Provisioning .

When installing a HotFix on a BIG-IP device, F5 best practices require:

Installing the base TMOS image on a new, unused boot volume (HD1.2)

This ensures the upgrade happens on a clean volume.

The existing active boot location remains untouched for rollback.

Installing the HotFix onto the SAME new boot volume (HD1.2)

HotFixes must be applied on top of a base version.

They cannot be installed on an empty volume.

They must match the base image version.

Activating the new boot volume (HD1.2)

The system reboots into the updated software stack.

Activation happens after base + HotFix installation is complete.

This sequence is exactly shown in Option C :

Install base Image in HD1.2

Install HotFix in HD1.2

Activate HD1.2

Why the other options are incorrect:

A. Install HotFix before base image

Impossible.

HotFix requires an installed base version first.

B. Installing HotFix on HD1.1 (active boot volume)

Not recommended.

Upgrading in-place removes rollback safety.

HotFix cannot be applied cleanly without applying base image first.

D. Activate HD1.2 before installing anything

You cannot activate an empty boot volume.

Activation only occurs after the base + HotFix software is installed.

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

The Service Check Date embedded in the BIG-IP license acts as a gating mechanism that determines eligibility for software updates. F5 enforces that the Service Check Date must be equal to or newer than the software release date of any BIG-IP version being installed. If the installed license carries a Service Check Date from two years ago, attempting to upgrade to a newly released BIG-IP software version — whose release date post-dates that Service Check Date — will fail, as the system validates this date during the upgrade process.

Option A is incorrect — generating and uploading a QkView to F5 iHealth is a diagnostic activity that requires no license validation or Service Check Date verification whatsoever.

Option C is incorrect — ASM signature and threat campaign updates are content updates, not platform software upgrades. These updates are independent of the Service Check Date requirement and do not trigger license validation checks during installation.

Only a platform software upgrade to a newly released BIG-IP version directly invokes the Service Check Date validation, mandating license renewal prior to the upgrade proceeding successfully.

Reference Topics: License Service Check Date, Software Upgrade Prerequisites, License Reactivation — BIG-IP Administration Study Guide.

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

When provisioning modules on a BIG-IP system, F5 provides specific resource allocation settings that define how system resources — CPU, memory, and disk — are distributed to each licensed module. The two valid and officially recognised allocation settings are Nominal and Dedicated .

Nominal instructs the system to allocate a moderate, balanced share of resources to the module. It allows the module to function effectively while sharing system resources with other provisioned modules. This is the most commonly used setting in multi-module deployments.

Dedicated allocates the maximum available system resources exclusively to a single module. When this setting is applied, it is typically the only module provisioned, as it consumes resources at a level that prevents other modules from operating concurrently in a meaningful capacity.

Option A — Maximum is not a valid BIG-IP provisioning allocation level; it does not appear in the official provisioning interface or documentation as a selectable resource tier.

Option C — Limited similarly does not exist as a defined resource allocation setting within BIG-IP module provisioning. It may superficially resemble valid terminology but has no standing in the official provisioning framework.

Administrators access these settings via System » Resource Provisioning in the Configuration Utility, where each licensed module displays its available allocation options.

Reference Topics: Module Resource Provisioning, Nominal vs. Dedicated Allocation, System Resource Management — BIG-IP Administration Study Guide.

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.