F5-CTS-LTM Practice Questions 1 — 50 Questions

Question 1

Which CLI command is used to view the real-time status of pool members and their current connection counts?

Accepted Answer

tmsh show ltm pool. The 'tmsh show ltm pool' command is the primary tool for administrators to inspect the current state of load-balanced resources. It provides immediate visibility into member health, active connections, and traffic statistics. Being proficient with this command is essential for daily monitoring and rapid incident response, as it allows operators to quickly identify overloaded nodes or servers that have unexpectedly failed their health checks during production operations.

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tmsh list ltm pool

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tmsh monitor ltm pool

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tmsh status ltm pool

Question 2

Refer to the exhibit. If a client connects to the BIG-IP and the persistence profile is applied, what happens when the session expires?

Accepted Answer

The cookie is removed when the browser session ends.. The 'expiration 0' setting in the cookie persistence profile indicates that the persistence cookie is a session cookie, which persists as long as the browser remains open. Once the browser is closed, the cookie is deleted. Understanding how session versus persistent cookies function is vital for LTM administrators to manage user experience and ensure that session stickiness is maintained correctly across different browser behaviors and application requirements.

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The cookie remains on the client machine until manually deleted.

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The BIG-IP forces the client to re-authenticate immediately.

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The cookie remains valid for 3600 seconds as the default.

Question 3

Which load balancing method is most appropriate for a pool where servers have significantly different hardware specifications and processing capabilities?

Accepted Answer

Ratio. When pool members have varying hardware specs, simple algorithms like Round Robin perform poorly because they send equal traffic to all servers regardless of their ability to handle it. 'Ratio' load balancing allows the administrator to assign a weight to each server, ensuring more powerful servers receive a higher proportion of traffic, which optimizes overall application performance and prevents the saturation of weaker servers.

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Round Robin

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Least Connections

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Observed

Question 4

Which profile is essential to enable when you need to inspect or manipulate HTTP traffic, such as inserting X-Forwarded-For headers?

Accepted Answer

HTTP Profile. The HTTP profile is required for any Layer 7 processing. Without an HTTP profile, the BIG-IP treats traffic as raw TCP streams. By enabling the HTTP profile, the LTM gains the ability to parse HTTP requests and responses, allowing for features like header manipulation, cookie persistence, and content switching, which are standard requirements for modern web application delivery controllers.

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TCP Profile

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Client SSL Profile

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FastL4 Profile

Question 5

What is the primary function of the 'OneConnect' profile in a BIG-IP LTM configuration?

Accepted Answer

To enable TCP connection reuse to backend servers.. The OneConnect profile enables connection pooling between the BIG-IP and the backend servers. By keeping backend connections open even after a client request is fulfilled, the BIG-IP can reuse these existing connections for subsequent requests. This reduces the overhead associated with the TCP three-way handshake for every new request, significantly lowering the CPU utilization on backend servers and improving overall latency.

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To perform SSL decryption for client-side traffic.

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To allow for HTTP header insertion.

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To enforce persistence based on client IP.

Question 6

Refer to the exhibit. The BIG-IP LTM is configured with a simple TCP monitor. Users report that while the BIG-IP shows the pool members as 'Up', they receive a '503 Service Unavailable' error when accessing the application. What is the most likely reason for this?

Accepted Answer

The application-level health check is missing or insufficient.. A TCP monitor only confirms that the port is open and the operating system is accepting connections, not that the application service is operational. In this case, the web server process might have crashed or be misconfigured, leading to an HTTP 503 response. The LTM treats the server as 'Up' because the TCP handshake succeeds, failing to detect the application-level failure requiring an HTTP monitor.

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The TCP monitor is configured with an incorrect port.

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The pool members are not responding to the TCP SYN packets.

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The load balancing algorithm is set to Round Robin.

Question 7

A company requires that traffic be load balanced based on server response time. The LTM must dynamically select the server that is currently responding the fastest. Which load balancing algorithm should be used?

Accepted Answer

Fastest. The 'Fastest' load balancing algorithm tracks the time it takes for a server to respond to a request. The BIG-IP uses this metric to dynamically direct new connections to the pool member that currently provides the lowest latency. This is highly effective in environments where server performance varies due to heterogeneous hardware or fluctuating application loads.

Answer

Round Robin

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Least Connections

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Observed

Question 8

Refer to the exhibit. Clients are reporting 'SSL Handshake Failure' errors. What is the most likely cause?

Accepted Answer

The cipher string excludes TLS 1.0, which some clients require.. The cipher string 'DEFAULT:!SSLv3:!TLSv1' explicitly disables TLS 1.0. Many legacy clients still require TLS 1.0 to establish a handshake. By excluding it, the BIG-IP is rejecting any connection attempt from clients that do not support TLS 1.1 or higher. This is a common configuration error when trying to harden security without auditing the client base's compatibility first.

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The certificate has expired.

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The virtual server is missing an HTTP profile.

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The key and certificate do not match.

Question 9

An administrator wants to optimize the performance of an HTTPS-based application. Which THREE configurations should they consider to reduce load on the backend servers?

Accepted Answer

Enable SSL termination on the BIG-IP.. Offloading resource-intensive tasks from the backend servers is a core function of the LTM. SSL offloading, HTTP compression, and connection pooling are key techniques. By performing decryption and compression on the BIG-IP, the backend servers are freed to focus on application logic, significantly improving response times and overall system scalability, while reducing the computational burden on the web server infrastructure.

Answer

Configure the default 'Round Robin' load balancing method.

Answer

Increase the maximum number of pool members.

Question 10

Refer to the exhibit. The pool members are marked down. A manual test shows that 'curl -v -H "Host: www.example.com" http://<member_ip>/health.php' returns 'OK'. What is the most likely issue?

Accepted Answer

The 'receive' string does not account for the entire HTTP response body.. The health monitor configuration requires exact string matching for the 'receive' field. If the server returns extra whitespace, headers, or different formatting than expected by the BIG-IP, the match will fail. The monitor configuration in the exhibit is correct in syntax, but the 'receive' string must match exactly the data found in the raw response body, which often differs from how a terminal-based curl output displays information.

Answer

The monitor is missing the 'interval' and 'timeout' parameters.

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The HTTP version in the send string is causing a protocol mismatch.

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The connection should be set to 'Keep-Alive' instead of 'Close'.

Question 11

Refer to the exhibit. A user connects to Virtual Server A, which uses the 'my_source_persistence' profile. The user is then redirected to Virtual Server B. Given the configuration, will the persistence record be honored?

Accepted Answer

No, because match-across-virtuals is disabled.. The persistence profile has 'match-across-virtuals' set to 'disabled'. Because this attribute is disabled, the BIG-IP will not share persistence information between Virtual Server A and Virtual Server B. When the user lands on Virtual Server B, the system will initiate a new load balancing decision instead of respecting the persistence session established on the first virtual server, which is crucial for managing multi-virtual server architectures.

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Yes, because the timeout is set to 180 seconds.

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Yes, because source-addr persistence is global.

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No, because the timeout must be set to indefinite.

Question 12

Which TWO of the following are primary benefits of using an iApp Template for BIG-IP deployment?

Accepted Answer

Simplified management by grouping related LTM objects into a single logical entity.. iApp templates provide a structured, simplified interface for deploying complex applications. By abstracting the creation of multiple objects (virtual servers, pools, profiles, iRules) into a single deployment unit, they reduce the risk of human error and configuration drift. These templates are essential for maintaining consistency across large environments and ensuring that best practices are followed during every configuration step.

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Automatic translation of proprietary application logic into F5 proprietary TCL scripts.

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Direct execution of remote SQL queries to backend database servers for load balancing.

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Automatic hardware upgrades of the BIG-IP platform when capacity is reached.

Question 13

You have a requirement to distribute traffic to pool members based on the total number of active connections each server is currently handling. Which load balancing method should be selected?

Accepted Answer

Least Connections (member). The 'Least Connections' method is the correct choice for load balancing based on active session counts. This algorithm dynamically tracks the current load on each server and directs new requests to the member with the fewest active connections. It is essential for application environments where individual requests vary significantly in duration or resource consumption, preventing any single server from becoming overwhelmed.

Answer

Round Robin

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Ratio (member)

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Observed (member)

Question 14

Refer to the exhibit. The web_pool is currently offline with zero active members. An LTM Specialist checks the backend servers and finds they are both responding to pings. What is the most likely reason for the pool being offline?

Accepted Answer

The health monitor is misconfigured or the service is down.. The pool status is 'offline' and 'children are down' despite servers being reachable via ping. This indicates the health monitor configured on the pool is failing, likely because the specific service (e.g., HTTP on port 80) is not responding or the monitor is misconfigured. Ping only tests network layer connectivity, whereas LTM monitors test application-layer availability, which is the standard for determining if a server can actually process traffic.

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The virtual server is disabled.

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The default route on the BIG-IP is missing.

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The SNAT pool is exhausted.

Question 15

Why would an LTM Specialist choose to implement a SNAT Automap instead of a SNAT pool?

Accepted Answer

To reduce administrative overhead for simple configurations.. SNAT Automap is the simplest way to manage source translation because it automatically uses the BIG-IP's floating self-IP address. It is ideal for environments where a dedicated pool of IP addresses is not required. This reduces administrative complexity and configuration overhead, which is beneficial for smaller deployments or scenarios where the backend servers only need to see the BIG-IP as the source of traffic.

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To increase security by using multiple source IP addresses.

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To prevent port exhaustion on the BIG-IP.

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To allow backend servers to track unique client IP addresses.

Question 16

An administrator implements Priority Group Activation on a pool containing four web servers. Two servers are assigned priority 10, and two servers are assigned priority 5. The minimum active members parameter is set to 2. One priority 10 member fails. What is the precise traffic distribution behavior of the BIG-IP system?

Accepted Answer

Traffic is balanced exclusively between the single remaining priority 10 member and the two priority 5 members.. Priority Group Activation directs traffic to the highest available priority group until the number of active members in that group drops below the specified minimum active members threshold. When one priority 10 member fails, one remains active, which is below the minimum threshold of 2, triggering activation of the lower priority group while keeping the remaining priority 10 member active.

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Traffic ceases entirely for all pool members until administrators manually intervene and adjust the priority group thresholds via TMOS.

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Traffic distribution shifts completely to the two priority 5 servers, and the remaining priority 10 server is taken offline immediately.

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Traffic is distributed strictly among the two priority 5 servers while the remaining priority 10 server acts as a standby hot spare.

Question 17

An administrator observes that the BIG-IP is not correctly load balancing traffic across all members of a pool. What is the most likely cause if the load balancing method is set to 'Least Connections'?

Accepted Answer

Persistence is enabled, causing the BIG-IP to bypass the load balancing algorithm for existing sessions.. The 'Least Connections' method is highly dependent on the accuracy of the connection table. If persistence is configured, the BIG-IP will ignore the least connections algorithm for any request that is part of an existing session. This is a frequent point of confusion where administrators expect even distribution but see skewed results because users are 'stuck' to specific servers due to their persistence records.

Answer

The pool members are in different subnets, preventing the load balancer from seeing all connections.

Answer

The 'Ratio' load balancing method is implicitly overriding the 'Least Connections' setting.

Answer

The TCP profile is set to 'OneConnect', which prevents the tracking of individual connections.

Question 18

Refer to the exhibit. Why would an administrator enable 'map-to-ipv6' in a source-address persistence profile?

Accepted Answer

It creates a unified persistence table for both IPv4 and IPv6 clients.. In dual-stack environments, both IPv4 and IPv6 clients might access the same application. The 'map-to-ipv6' feature ensures that IPv4 addresses are normalized into an IPv6-compatible format within the persistence table. This creates a unified persistence context, allowing the BIG-IP to correctly track and persist traffic from both address types to the same backend server, maintaining session consistency across different network protocols.

Answer

It forces all traffic to be converted to IPv6 for backend server processing.

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It allows the LTM to translate IPv6 client requests to IPv4 backend servers.

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It is required for performance optimization on the BIG-IP management plane.

Question 19

An administrator needs to modify the HTTP response header to hide the server version for security reasons. Which tool is most appropriate?

Accepted Answer

An iRule in the 'HTTP_RESPONSE' event with 'HTTP::header remove Server'.. An iRule using the 'HTTP_RESPONSE' event is the most flexible way to modify headers. Using the 'HTTP::header remove' command, an administrator can strip sensitive version information from the 'Server' header before the response reaches the client. This is a common security hardening task that prevents potential attackers from fingerprinting the backend server version and identifying known vulnerabilities associated with that specific platform.

Answer

A Local Traffic Policy with a 'header' modify action.

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A customized HTTP profile that blocks the 'Server' header.

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A custom monitor with 'header-strip' enabled.

Question 20

Refer to the exhibit. What is the impact of using the 'tcp-lan-optimized' profile on this virtual server?

Accepted Answer

It is inappropriate if the clients are connecting over the Internet.. The 'tcp-lan-optimized' profile is designed for high-speed, low-latency environments like LANs. It modifies TCP settings to be less aggressive than 'tcp-wan-optimized'. Using it on a connection where the client is accessing over the internet (WAN) can result in poor performance, as the settings do not account for the high latency and packet loss typically encountered on public networks compared to local infrastructure.

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It improves performance for clients connecting over long-distance WAN links.

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It provides faster window scaling for high-latency connections.

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It disables TCP keep-alives to save memory on the BIG-IP.