[Jul-2026] F5 F5CAB3 Exam Practice Test Questions - BraindumpQuiz
Updated Certification Exam F5CAB3 Dumps - Practice Test Questions
NEW QUESTION # 43
A virtual server is configured to offload SSL from a pool of backend servers. When users connect to the virtual server, they successfully establish an SSL connection but no content is displayed. A packet trace performed on the server shows that the server receives and responds to the request. What should a BIG-IP Administrator do to resolve the problem? (Choose one answer)
- A. enable SNAT
- B. disable SNAT
- C. enable Server SSL profile
- D. disable Server SSL profile
Answer: A
Explanation:
This scenario describes a classic case of asymmetric routing in a "one-arm" or non-gateway deployment.
When a BIG-IP system is configured for SSL offloading, the following traffic flow occurs:
* Client-Side: The client establishes a successful SSL/TLS handshake with the Virtual Server. This explains why the user can "successfully establish an SSL connection."
* Server-Side: The BIG-IP decrypts the traffic and forwards it as plain HTTP to the backend server. The packet trace confirms the server receives the HTTP GET request and responds with the content.
* The Routing Failure: By default, the BIG-IP system preserves the client's original source IP address. If the backend server's default gateway is not the BIG-IP system (or if the server is on the same subnet as the client), the server will attempt to send the response directly back to the client's IP address, bypassing the BIG-IP.
* Stateful Drop: Because the BIG-IP is a Full Proxy, it expects the response to return through its own internal state table to be encrypted and sent back to the client. Since the response bypasses the BIG-IP, the BIG-IP connection eventually times out, and the client receives no data despite the server having sent it.
Solution (SNAT): Enabling Secure Network Address Translation (SNAT), specifically SNAT Auto Map, ensures that the BIG-IP replaces the client's source IP with its own internal self-IP before sending the request to the server. This forces the server to send the response back to the BIG-IP, allowing the BIG-IP to complete the transaction and deliver the content to the user.
NEW QUESTION # 44
The BIG-IP Administrator is investigating whether better TCP performance is possible for a virtual server.
Which built-in profile should be tried first? (Choose one answer)
- A. f5-tcp-progressive
- B. f5-tcp-legacy
- C. f5-tcp-mobile
- D. No option
Answer: A
Explanation:
BIG-IP provides several built-in TCP profiles optimized for different traffic patterns and network conditions. When attempting to improve general TCP performance, the recommended starting point is f5-tcp-progressive.
According to the BIG-IP Administration: Data Plane Configuration documentation:
f5-tcp-progressive is designed as a balanced, general-purpose TCP optimization profile.
It dynamically adjusts TCP behavior to improve throughput and latency for most enterprise applications.
It is the recommended first-choice profile when tuning TCP performance before moving to more specialized profiles.
Why the other options are incorrect:
A . f5-tcp-legacy
This profile exists for backward compatibility and does not include modern TCP optimizations.
C . f5-tcp-mobile
This profile is optimized specifically for high-latency, lossy mobile networks and is not suitable for general-purpose environments.
D . No option
BIG-IP explicitly provides built-in TCP profiles for performance tuning; using none would forgo optimization opportunities.
Correct Resolution:
The administrator should first apply f5-tcp-progressive to evaluate potential TCP performance improvements before considering more specialized profiles.
NEW QUESTION # 45
The BIG-IP Administrator has to provide encrypted communication between the users and the virtual server they access. Multiple hostnames are configured in DNS with the same IP address. Which profile type and setting in the profile should be used? (Choose one answer)
- A. Server SSL, Server Name
- B. Server SSL, Client Name
- C. Client SSL, Server Name
- D. Client SSL, Client Name
Answer: C
Explanation:
To provide encrypted communication between users and a virtual server, the BIG-IP system acts as a transparent SSL/TLS proxy. The administrative configuration required for this is a Client SSL profile.
When multiple hostnames (FQDNs) are associated with a single IP address, the system must determine which SSL certificate to present to the client during the initial TLS handshake. This is achieved using an extension of the TLS protocol called Server Name Indication (SNI).
The configuration logic is as follows:
* Profile Type: The Client SSL profile is responsible for terminating the SSL connection from the client (the user) to the BIG-IP system.
* The Setting: Within the Client SSL profile (under the "Advanced" view), there is a field specifically called Server Name. By entering the specific hostname (e.g., www.example.com) in this field, the BIG- IP system can match the hostname requested by the client in the ClientHello message to the correct profile.
* Implementation: The administrator typically creates multiple Client SSL profiles-one for each hostname-and assigns them all to the same virtual server. One of these profiles must be designated as the Default SSL Profile for SNI to handle requests where the client does not provide a hostname or provides one that does not match any specific profile.
By using the Client SSL profile and the Server Name setting, the BIG-IP system ensures that each user receives the correct certificate for the specific site they are trying to reach, even though all sites share a single virtual server IP.
NEW QUESTION # 46
For a given Virtual Server, the BIG-IP must perform SSL Offload and negotiate secure communication over TLSv1.2 only. What should the BIG-IP Administrator do to meet this requirement?
- A. Configure a custom SSL Profile (Server) and select no TLSv1 in the options list
- B. Configure a custom SSL Profile (Client) and select no TLSv1 in the options list
- C. Configure a custom SSL Profile (Server) with a custom TLSv1.2 cipher string
- D. Configure a custom SSL Profile (Client) with a custom TLSv1.2 cipher string
Answer: D
Explanation:
To fulfill the requirement of "SSL Offload" limited to "TLSv1.2 only," the administrator must focus on the client-side of the connection. SSL Offload means the BIG-IP terminates the encrypted connection from the user, processes the traffic (often as plain text internally), and optionally sends it to the backend. The profile responsible for this termination and the initial negotiation with the client's browser is the Client SSL Profile.
A custom Client SSL Profile must be created because the default clientssl profile typically allows a broad range of protocols for compatibility (including TLS 1.0, 1.1, and 1.2). To restrict communication specifically to TLS 1.2, the administrator modifies the Ciphers string within the profile. Using a string such as DEFAULT:!SSLv3:!TLSv1:!TLSv1.1 or specifically defining TLSv1.2-only suites ensures that the BIG-IP will reject any handshake attempts from older, less secure protocols.
Server SSL Profiles (Options B and C) are used for the encryption between the BIG-IP and the backend nodes, which is not what is requested here. Simply selecting "no TLSv1" in an options list (Option D) is insufficient and often refers to older versions of the software; the modern and standard way to control protocol negotiation on a BIG-IP is through the precise application of Cipher Strings within the Client SSL profile. This ensures compliance with security standards like PCI-DSS while providing the offloading benefits to the backend infrastructure.
NEW QUESTION # 47
The BIG-IP Administrator has to provide encrypted communication between users and the virtual server they access. Multiple hostnames are configured in DNS with the same IP address.
Which profile type and setting in the profile should be used? (Choose one answer)
- A. Server SSL, Server Name
- B. Server SSL, Client Name
- C. Client SSL, Server Name
- D. Client SSL, Client Name
Answer: C
Explanation:
When multiple hostnames resolve to the same IP address and encrypted communication is required, the BIG- IP must be able to present the correct SSL certificate based on the hostname requested by the client. This is accomplished using Server Name Indication (SNI).
According to BIG-IP Administration: Data Plane Configuration documentation:
* SNI is a client-side TLS extension, where the client includes the requested hostname during the SSL handshake.
* BIG-IP evaluates this hostname using the Client SSL profile, not the Server SSL profile.
* The "Server Name" setting in the Client SSL profile enables BIG-IP to select the appropriate SSL certificate for the requested hostname.
Why option C is correct:
* Client SSL profile handles inbound (client-side) encryption.
* Server Name enables SNI-based certificate selection when multiple DNS names share the same virtual server IP.
Why the other options are incorrect:
* A. Client SSL, Client NameThere is no Client SSL setting called Client Name for SNI certificate selection.
* B. Server SSL, Server NameServer SSL is used for encryption between BIG-IP and backend servers, not for client-side hostname identification.
* D. Server SSL, Client NameServer SSL does not process client-requested hostnames during TLS negotiation.
Correct Resolution:
Configure a Client SSL profile and enable the Server Name (SNI) setting to support multiple encrypted hostnames on the same virtual server IP.
NEW QUESTION # 48
A BIG-IP Administrator creates a new VLAN on BIG-IP Cluster Member A and attaches an interface to it.
Although the Auto Config Sync is in place, the new VLAN does NOT show up on Cluster Member B. What should the BIG-IP Administrator do to ensure the new VLAN is configured on each Cluster Member?
- A. Configure the new VLAN manually on Cluster Member B
- B. Enable the Interface that is attached to the new VLAN on Cluster Member A
- C. Reset the Device Trust of the BIG-IP Cluster on either Cluster Member
- D. Configure a Default Route for the new VLAN on Cluster Member A
Answer: A
NEW QUESTION # 49
Refer to the exhibit.
A BIG-IP Administrator configures a Virtual Server to handle HTTPS traffic. Users report that the application is NOT working. Which additional configuration is required to resolve this issue?
- A. Configure SSL Profile (Client)
- B. Configure SSL Profile (Server)
- C. Configure Protocol Profile (Server)
- D. Configure Service Port to HTTP
Answer: A
Explanation:
According to the provided exhibit, the " SSL Profile (Client) " section in the Virtual Server configuration is empty. For a BIG-IP system to process HTTPS traffic, it must act as an SSL/TLS endpoint. This process, known as SSL Termination or SSL Offload, requires the assignment of a Client SSL Profile to the Virtual Server. Without this profile, the BIG-IP does not have the necessary certificate and private key information to perform the SSL handshake with the client ' s browser. Consequently, when a user attempts to connect via HTTPS, the TCP connection may establish, but the SSL handshake will fail because the BIG-IP will not know how to decrypt the incoming encrypted packets.
A Client SSL profile defines the ciphers, certificates, and keys that the BIG-IP uses to communicate securely with the client. In a standard HTTPS deployment, the BIG-IP decrypts the traffic and can then send it to the backend pool members either as plain text (header insertion/manipulation) or re-encrypt it using a Server SSL profile. While a Server SSL profile (Option C) is needed if the backend servers themselves require HTTPS, the initial failure for a user reaching a Virtual Server is almost always the lack of a Client SSL profile to terminate the user ' s connection. Changing the Service Port to HTTP (Option D) would be incorrect because the goal is to handle HTTPS traffic (typically port 443). Assigning the " clientssl " or a custom client-side profile from the " Available " list to the " Selected " list in the GUI is the mandatory step to make the Virtual Server operational for secure web traffic.
NEW QUESTION # 50
Exhibit:
Due to a change in application requirements, a BIG-IP Administrator needs to modify the configuration of a Virtual Server to include a Fallback Persistence Profile. Which persistence profile type should the BIG-IP Administrator use for this purpose?
- A. Source Address Affinity
- B. Hash
- C. SSL
- D. Universal
Answer: A
Explanation:
In a BIG-IP environment, a Fallback Persistence Profile is utilized as a secondary " stickiness " mechanism when the primary (Default) persistence method fails to provide a valid persistence record. For example, if a Virtual Server uses HTTP Cookie Persistence as its primary method, but a client's browser has cookies disabled, the BIG-IP will be unable to find a persistence cookie in the request. Without a fallback method, the system would treat every request from that client as a new, independent connection, potentially breaking the application session.
Source Address Affinity (also known as Source Address Persistence) is the most common and standard choice for a fallback profile. It operates at the network layer (Layer 3) by tracking the client's source IP address.
Because every IP packet contains a source address, this method is virtually guaranteed to work even when application-layer data (like Cookies or SSL Session IDs) is missing or encrypted beyond the BIG-IP ' s visibility. While Universal (Option A) and Hash (Option D) profiles are highly flexible and can use iRules to persist on almost any data, they require specific configuration and logic that may not always be present or valid. SSL persistence (Option C) relies on the SSL Session ID, which frequently changes due to modern browser security practices (session renegotiation), making it less reliable than Source Address Affinity. By configuring Source Address Affinity as the fallback, the administrator ensures that the BIG-IP has a " safety net " to maintain session integrity based on the client ' s IP address when the more granular cookie-based persistence is unavailable.
NEW QUESTION # 51
Refer to the exhibit.
A BIG-IP Administrator configures a new VLAN on an HA pair of devices that does NOT yet have any traffic. This action causes the assigned traffic group to fail over to the standby device. Which VLAN setting should be changed to prevent this issue?
- A. Source Check
- B. Customer Tag
- C. Auto Last Hop
- D. Fail-safe
Answer: D
Explanation:
The exhibit shows the advanced configuration of a VLAN where the Fail-safe option is checked. VLAN Fail- safe is a high-availability feature used to monitor network connectivity on a specific VLAN. When enabled, the BIG-IP system monitors the VLAN for network traffic. If the system does not detect any " useful " traffic on the VLAN within the specified Fail-safe Timeout (which is 90 seconds in the exhibit), it attempts to generate traffic by pinging the default gateway or other devices. If it still detects no traffic, the BIG-IP concludes that the VLAN is unreachable or the network interface has failed, and it triggers a " Fail-safe Action " -in this case, " Reboot " or a failover to the peer device in the HA group.
Because the administrator has just created a new VLAN that " does NOT yet have any traffic, " the Fail-safe mechanism triggers immediately after the 90-second timeout period. Since no devices are yet communicating on this VLAN, the BIG-IP incorrectly assumes there is a hardware or cabling failure and forces a failover to ensure the standby device (which might have better connectivity) takes over. To prevent this unwanted failover, the administrator should uncheck the Fail-safe box for that specific VLAN until the VLAN is fully populated with active nodes and regular traffic. Once the application is live and traffic is flowing, Fail-safe can be re-enabled to provide an additional layer of redundancy. Auto Last Hop (Option A) and Source Check (Option B) are routing and security features that do not trigger HA failover events.
NEW QUESTION # 52
A BIG-IP Administrator needs to configure health monitors for a pool containing HTTP, HTTPS, FTP, and SSH services.
Which configuration ensures accurate member status?
- A. All monitors with Availability Requirement = at least one
- B. All monitors with Availability Requirement = all
- C. HTTP and HTTPS only
- D. ICMP + TCP with all
Answer: A
Explanation:
Using "at least one" ensures each member is marked up based on its relevant service monitor.
NEW QUESTION # 53
In a pool there are 2 pool members out of the 5 members that are older servers. The number of connections these can handle is less than the other 3 pool members. Which load balancing method would allow more traffic to be directed to the newer servers? (Choose one answer)
- A. Least Connections (member)
- B. Round Robin
- C. Global Availability
- D. Weighted Least Connections (member)
Answer: D
Explanation:
When a pool contains servers with heterogeneous hardware capabilities (differing CPU, RAM, or connection limits), a static load balancing method like Round Robin is ineffective because it distributes requests equally, regardless of the server's capacity. To optimize traffic distribution for newer, more powerful servers, a dynamic or weighted method is required.
Weighted Least Connections (member): This is the ideal method for this scenario. It combines two factors:
Least Connections: It first checks the current active connection count to ensure traffic goes to the least busy server.
Weight (Ratio): It allows the administrator to assign a "Ratio" value to each pool member. Newer servers can be assigned a higher ratio (e.g., 3) while older servers are assigned a lower ratio (e.g., 1). The BIG-IP system uses these weights to disproportionately favor the newer servers even when connection counts are similar.
Why other options are incorrect:
Global Availability: This is primarily a GSLB (Global Server Load Balancing) or specific LTM priority group concept where traffic is sent to the first available member in a list until it fails, then moves to the next. It does not load balance based on capacity.
Round Robin: This passes each new connection request to the next server in line, treating the old and new servers exactly the same.
Least Connections (member): While this sends traffic to the server with the fewest active connections, it assumes all servers are equal. If an old server and a new server both have 10 connections, they are treated as equally capable of taking the 11th, which is not true in this scenario.
NEW QUESTION # 54
Which two load balancing methods consider all the connections the BIG-IP has between it and each backend application server (Pool Member) when making a load balancing decision for a new connection?
- A. Round Robin
- B. Ratio (member)
- C. Least Connections (node)
- D. Weighted Least Connections (node)
Answer: C,D
Explanation:
The two load balancing methods that consider all connections between the BIG-IP and each backend node
- not just connections to a specific pool member - are Least Connections (node) and Weighted Least Connections (node) .
The critical distinction here lies in the node-level scope of evaluation. A node represents the backend server ' s IP address, regardless of how many services or ports it may be serving. Therefore:
* Least Connections (node) directs new connections to the node with the fewest total active connections across all services on that server, providing a holistic connection-count perspective.
* Weighted Least Connections (node) operates identically but factors in an administrator-defined ratio weight, allowing servers with greater capacity to proportionally absorb more connections while still evaluating total node-level connection counts.
By contrast:
* Ratio (member) distributes traffic based on a static weight ratio and does not dynamically evaluate current connection counts.
* Round Robin distributes traffic sequentially in rotation, completely ignoring current connection states on any node or member.
The node-based methods are particularly valuable in environments where a single backend server hosts multiple pool members across different ports, ensuring the server ' s overall load - not just per-service load
- governs balancing decisions.
Reference: BIG-IP Administration - Data Plane Configuration, Module: Load Balancing Methods - Member vs. Node Scope.
NEW QUESTION # 55
A BIG-IP Administrator is creating a new Trunk on the BIG-IP device. What objects should be added to the new Trunk being created?
- A. IP addresses
- B. Interfaces
- C. VLANs
- D. Network routes
Answer: B
Explanation:
In F5 BIG-IP architecture, a Trunk is a logical aggregation of physical interfaces designed to increase bandwidth and provide link redundancy through 802.3ad Link Aggregation Control Protocol (LACP).
When creating a Trunk object within the BIG-IP configuration, the administrator must assign physical Interfaces to it - these are the underlying hardware ports (e.g., 1.1, 1.2, 1.3) that will be bundled together to form the aggregated logical link.
It is critical to understand the layered object hierarchy on the BIG-IP platform:
* Interfaces # assigned to Trunks
* Trunks (or individual Interfaces) # assigned to VLANs (as tagged or untagged members)
* VLANs # assigned Self IP addresses
* Self IPs / Routes # configured at the network layer above
VLANs are not added to a Trunk; rather, a Trunk is added as a member of a VLAN. IP addresses and network routes are configured independently at a higher abstraction layer and have no direct association with Trunk creation.
This layered design ensures proper separation of concerns across the data plane. Misunderstanding this hierarchy is a common configuration error that can result in traffic forwarding failures.
Reference: BIG-IP Administration - Data Plane Configuration, Module: Network Objects - Interfaces, Trunks, and VLANs.
NEW QUESTION # 56
A Standard Virtual Server for a web application is configured with Automap for the Source Address Translation option. The original source address of the client must be known by the backend servers. What should the BIG-IP Administrator configure to meet this requirement?
- A. An HTTP Transparent profile
- B. The Virtual Server type as Performance (HTTP)
- C. An HTTP profile to insert the X-Forward-For header
- D. A SNAT Pool with the client IP
Answer: C
Explanation:
SNAT Automap is a common configuration that replaces the client ' s original source IP address with one of the BIG-IP ' s self IP addresses. This ensures that the backend servers send return traffic back through the BIG-IP, which is necessary for the ADC to process the traffic correctly. However, a side effect of SNAT is that the backend servers only see the BIG-IP ' s IP in their logs, losing visibility into the true identity of the client.
To resolve this while still using SNAT for routing purposes, the administrator must configure the BIG-IP to " pass " the client ' s IP address at the application layer. This is achieved by using an HTTP Profile with the Insert X-Forwarded-For setting enabled. When this profile is applied to the Virtual Server, the BIG-IP intercepts the HTTP request, adds a header (X-Forwarded-For) containing the client ' s original IP, and then forwards the modified request to the server. The backend web server can then be configured to read this header and log the original client IP instead of the BIG-IP ' s SNAT address.
Other options are incorrect for this requirement. Performance (HTTP) (Option A) is a virtual server type optimized for speed but often lacks the full Layer 7 header manipulation capabilities of a Standard Virtual Server. SNAT Pool with the client IP (Option C) is technically impossible as SNAT pools use static, pre- defined IPs. There is no such thing as an HTTP Transparent profile (Option D) in standard BIG-IP administration for this purpose. The X-Forwarded-For header insertion within the HTTP profile is the standard procedural method for maintaining client visibility in SNAT-enabled environments.
NEW QUESTION # 57
DNS queries from internal DNS servers fail when sent through a BIG-IP Virtual Server.
Which Virtual Server property should be changed?
- A. Protocol to UDP
- B. Protocol Profile (Client) to DNS_OPTIMIZED
- C. Source Address to subnet
- D. Type to Performance (HTTP)
Answer: A
Explanation:
Standard DNS queries use UDP. Configuring the Virtual Server for TCP causes DNS traffic to fail.
NEW QUESTION # 58
A Standard Virtual Server for a web application is configured with Automap for the Source Address Translation option. The original source address of the client must be known by the backend servers. What should the BIG-IP Administrator configure to meet this requirement?
- A. An HTTP Transparent profile
- B. The Virtual Server type as Performance (HTTP)
- C. An HTTP profile to insert the X-Forward-For header
- D. A SNAT Pool with the client IP
Answer: C
Explanation:
SNAT Automap is a common configuration that replaces the client's original source IP address with one of the BIG-IP's self IP addresses. This ensures that the backend servers send return traffic back through the BIG- IP, which is necessary for the ADC to process the traffic correctly. However, a side effect of SNAT is that the backend servers only see the BIG-IP's IP in their logs, losing visibility into the true identity of the client.
To resolve this while still using SNAT for routing purposes, the administrator must configure the BIG-IP to
"pass" the client's IP address at the application layer. This is achieved by using an HTTP Profile with the Insert X-Forwarded-For setting enabled. When this profile is applied to the Virtual Server, the BIG-IP intercepts the HTTP request, adds a header (X-Forwarded-For) containing the client's original IP, and then forwards the modified request to the server. The backend web server can then be configured to read this header and log the original client IP instead of the BIG-IP's SNAT address.
Other options are incorrect for this requirement. Performance (HTTP) (Option A) is a virtual server type optimized for speed but often lacks the full Layer 7 header manipulation capabilities of a Standard Virtual Server. SNAT Pool with the client IP (Option C) is technically impossible as SNAT pools use static, pre- defined IPs. There is no such thing as an HTTP Transparent profile (Option D) in standard BIG-IP administration for this purpose. The X-Forwarded-For header insertion within the HTTP profile is the standard procedural method for maintaining client visibility in SNAT-enabled environments.
NEW QUESTION # 59
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