F5 BIG-IP Administration Install, Initial Configuration, and Upgrade F5CAB1 Exam Dumps: Updated Questions & Answers (May 2026)

The exhibit shows a Self IP with:

VLAN: Data

Port Lockdown: Allow None

Impact of “Allow None” on SNMP

When a Self IP is configured with:

Port Lockdown: Allow None

the BIG-IP blocks all services and ports except a few hardcoded HA communication ports.

This means:

UDP/161 (SNMP) is blocked

UDP/162 (SNMP traps) is blocked

The SNMP server cannot poll or receive data from the BIG-IP through this Self IP

SNMP relies on access through the Self IP if out-of-band (mgmt interface) is not used.

Thus, the issue is directly caused by Port Lockdown = Allow None , which prevents SNMP communication.

Why the other options are incorrect:

B. Traffic Group must use a floating Traffic Group

SNMP polling does not require floating Self IPs.

Floating groups apply to HA failover IPs, not SNMP functionality.

C. VLAN/Tunnel must allow All VLANs

Self IPs are always bound to a VLAN; SNMP does not require All VLANs.

As long as the Self IP belongs to a reachable VLAN, SNMP can work.

D. Configuration is correct

It is not correct: Allow None blocks SNMP and is the problem.

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.

The BIG-IP management interface (MGMT port) is controlled through System settings , not through the Network menu.

SSH access on the management interface is configured here:

System → Configuration → Device → General → SSH Access / SSH IP Allow

This section allows the administrator to:

Enable or disable SSH service

Restrict SSH access to specific IP addresses or subnets

Apply security policies to the management interface

Why the other options are incorrect:

A. Network > Interfaces

Used for data-plane physical interface settings, not management plane SSH restrictions.

B. Network > Self IPs

Controls in-band management or data-plane access, not the dedicated management port.

D. System > Platform

Used for hostname, time zone, LCD contrast, hardware settings — not SSH security on the management port.

Therefore, restricting SSH access to the management interface must be done under:

✔ System → Configuration → Device → General

Which corresponds to Option C .

The BIG-IP has two distinct planes:

Management-plane → handled entirely by the management interface (MGMT)

Data-plane (TMM) → handles Self IPs, VLAN interfaces, and traffic processing

To capture traffic on the management interface, only the management-side NICs may be used:

mgmt → Logical name for the management interface

eth0 → Physical Linux interface mapped to the management port on most BIG-IP platforms

Both of these correctly capture inbound/outbound WebUI (HTTPS/443) traffic on the management port.

Why the correct answers are A and B

A. tcpdump -i eth0 -n port 443

On BIG-IP appliances and VMs, the management port maps to eth0 at the Linux OS level.

Capturing on eth0 correctly shows HTTPS traffic to the WebUI.

B. tcpdump -i mgmt -n port 443

mgmt is the BIG-IP alias for the management interface.

This is the preferred and most explicit capture interface for management-plane packet captures.

Why the other options are incorrect:

C. tcpdump -i 0.0

Interface 0.0 is the TMM switch interface used for data-plane packet captures.

It does NOT capture management-plane traffic.

D. tcpdump -i tun0

Used for tunnel interfaces (IPsec, VXLAN, etc.)

Not related to management access.

E. tcpdump -i management

There is no interface named management on BIG-IP.

The correct names are mgmt or eth0.

Provisioning determines:

Which BIG-IP modules are enabled (LTM, ASM, APM, AFM, DNS, etc.)

Their provisioning levels (None, Minimal, Nominal, Dedicated)

Two accurate ways to view provisioning settings are:

A. GUI — System → Resource Provisioning → Module Allocation

This is the primary GUI screen showing:

All modules

Their provisioning level

System resource distribution impact

Administrators commonly use this page to confirm or change module provisioning.

D. TMSH — list /sys provision

This tmsh command displays each module and its provisioning level:

sys provision ltm { level nominal }

sys provision asm { level none }

This is the authoritative CLI method for checking module provisioning configurations.

Why the other options are incorrect:

B. show /sys provision

Shows runtime information but not the actual configuration levels .

list is the correct command for configuration details.

C. Statistics → Module Statistics

Shows performance statistics, NOT provisioning status.

Therefore, the correct responses are A and D .

When installing a BIG-IP software version with a HotFix on a new boot volume , F5 requires that both the base TMOS image and the HotFix image be installed together as part of the same installation workflow.

The correct process is:

Specify the base TMOS ISO

Specify the HotFix ISO that corresponds to that base version

Instruct the system to create a new boot volume

Install both images into that new volume

This is achieved with the following tmsh syntax:

tmsh install /sys software BIGIP- < version > .iso hotfix Hotfix-BIGIP- < version > -ENG.iso create-volume HD1.2

This command:

Installs the base image first

Applies the HotFix on top of the base image

Creates and installs everything on HD1.2

Leaves the currently active volume untouched for rollback

Why the other options are incorrect

A. Installing only the hotfix

A HotFix cannot be installed by itself on a new volume. A base image must already be present.

C. Using create instead of install

The create keyword is not valid for software installation operations.

D. Using copy

The copy command does not install software images or hotfixes.

The Port Lockdown feature controls which services a Self-IP will respond to.

Setting a Self-IP to Allow None means:

The Self-IP will not accept any traffic except the very limited, hard-coded HA ports such as TCP 4353 used for device trust and configuration sync.

All other HA ports , including those needed for network failover and other HA mechanisms, are blocked .

When essential HA services cannot communicate, each device assumes its peer is down.

This results in:

HA failover misbehavior

Both devices thinking the other is offline

Potential active-active condition , which is not intended and can cause traffic disruption

Thus, Allow None can break HA functionality unless the Self-IP is not used for HA links.

When logged into the bash shell of a BIG-IP system, there are two valid ways to view the management-ip address:

A. tmsh list /sys management-ip

Even from the bash shell, the administrator can enter a tmsh command by typing:

tmsh list /sys management-ip

This displays:

Management IP address

Netmask

Any configured management routes

This is the official tmsh method for viewing the management-ip configuration.

C. ifconfig mgmt

In the underlying Linux OS, the management interface maps to the mgmt interface.

Running:

ifconfig mgmt

displays:

Assigned management IP

Netmask

Link-level status

This is a valid Linux-level method used frequently for troubleshooting.

Why the other options are incorrect:

B. show mgmt ip

Not a valid bash or tmsh command on BIG-IP.

D. list / sys management-ip

Missing the tmsh prefix.

In bash, this will generate a syntax error.

The correct form requires:

tmsh list /sys management-ip

The HTTPD allow list controls which IP addresses or subnets may access the Configuration Utility (TMUI) on the BIG-IP system. The Administrator already has two subnets allowed and needs to add a single host IP to the existing list.

The object /sys httpd allow supports actions such as add , delete , and replace-all-with .

Because the goal is to add one more entry without removing the existing permitted subnets, the correct command is:

modify /sys httpd allow add { 172.28.32.22 }

This appends the new host to the existing list while preserving the previously configured networks.

Why the other options are incorrect:

Option A (replace-all-with) would overwrite the entire allow list, removing existing permitted subnets—unacceptable.

Option B (delete) would remove the existing networks and not add the required host.

Therefore, the correct administrative action is to add the jump host’s IP.

In BIG-IP, software images are installed on boot volumes (for example, HD1.1, HD1.2, HD1.3, etc.).

To install software on a new volume , the administrator must instruct the system to create a new boot location before installation.

There are two correct ways to create a new volume:

A. tmsh command (with correct syntax)

tmsh install software image /shared/images/BIGIP- < version > .iso volume HD1.5 create-volume

This syntax correctly includes:

install software image

full path to ISO (/shared/images/...)

volume name (HD1.5)

create-volume keyword

This instructs BIG-IP to create the new boot volume as part of the installation.

C. Using the GUI → System > Disk Management

From the Disk Management menu, the administrator can:

Select “New Volume”

Enter the volume identifier (e.g., HD1.5)

Apply changes

This GUI method is officially supported and explicitly creates a new boot volume before installing the software.

Why the other options are incorrect:

B. Incorrect tmsh syntax

Missing /shared/images/ path

Incorrect command structure

D. Incorrect command structure

Missing required keywords and correct command hierarchy

E. Software Management → Install does NOT create volumes

This installs to an existing volume only

The GUI install dialog does not create new boot volumes

Thus, only Option A and Option C properly create a new software volume.