F5 301b Practice Test Questions, Exam Dumps

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301b F5 Practice Test Questions and Exam Dumps

Question 1

A virtual server has a OneConnect profile applied, and the LTM Specialist wants all client source IP addresses within the 10.10.10.0/25 range to reuse the same server-side connection.

What source mask should be used in the OneConnect profile to accomplish this?

A. 0.0.0.0
B. 255.255.255.0
C. 255.255.255.128
D. 255.255.255.224
E. 255.255.255.255

Correct answer: C

Explanation:

The OneConnect feature in F5 BIG-IP systems is designed to enable connection reuse on the server side by multiplexing multiple client-side connections onto fewer server-side connections. This is done to increase efficiency and reduce the overhead of establishing new TCP connections between the BIG-IP system and the pool members.

OneConnect uses a source mask to determine which client connections are considered equivalent for the purposes of server-side connection reuse. The source mask defines how much of the client’s source IP address is used in determining a match for connection reuse.

In this scenario, the client IP range is defined as 10.10.10.0/25. This subnet includes all IP addresses from 10.10.10.0 to 10.10.10.127. This is a 25-bit subnet, which corresponds to the subnet mask 255.255.255.128.

By setting the OneConnect profile’s source mask to 255.255.255.128, the BIG-IP system will treat all connections from clients in the 10.10.10.0/25 range as eligible for server-side connection reuse. That means if a client at 10.10.10.10 and another client at 10.10.10.100 both initiate sessions, the system will allow these connections to share an existing server-side connection because they fall under the same /25 network.

Let’s briefly examine why the other options are incorrect:

Option A (0.0.0.0): This allows the broadest possible sharing because it matches all IP addresses. It would allow clients from any IP to share connections, which may not be acceptable for security or session isolation reasons.
Option B (255.255.255.0): This corresponds to a /24 network (10.10.10.0 to 10.10.10.255), which includes more IPs than the specified /25 range. This would allow connection reuse for clients outside the desired range.
Option D (255.255.255.224): This is a /27 mask and only includes 32 IPs. This would be too narrow to cover the full 10.10.10.0/25 range.
Option E (255.255.255.255): This is the most restrictive and would prevent any sharing because it requires the source IPs to be identical. No connection reuse would occur unless it’s the exact same client IP.

Therefore, to allow clients in the 10.10.10.0/25 network to reuse server-side connections without allowing others outside that range to do so, the correct source mask is 255.255.255.128.

Correct answer: C

Question 2

In a client/server environment, an LTM device is load balancing telnet and SSH applications and there is significant packet delay.

Which setting in the TCP profile should be adjusted to reduce the amount of packet delay?

A. disable Bandwidth Delay
B. disable Nagle's Algorithm
C. enable Proxy Maximum Segment
D. increase Maximum Segment Retransmissions

Correct answer: B

Explanation:

In a load-balanced environment, packet delays can sometimes occur due to the way data is handled between the client and server, especially with TCP-based protocols like Telnet and SSH. Each of these settings in the TCP profile affects the way the transmission control protocol (TCP) behaves in different ways.

A. disable Bandwidth Delay:

This setting is related to the Bandwidth Delay product, which combines the bandwidth and the round-trip time (RTT) to calculate how much data should be sent. Disabling this would not necessarily reduce packet delay in Telnet and SSH applications, as it is more of a general setting for optimizing bandwidth usage rather than a specific fix for delay issues in TCP-based connections.

B. disable Nagle's Algorithm:

Nagle's Algorithm is a method used to reduce the number of small packets sent over the network by combining small messages into one larger packet. While this reduces network overhead, it can also introduce delays if the application requires small packets to be sent immediately, which is often the case with interactive applications like Telnet and SSH. By disabling Nagle's Algorithm, you allow smaller packets to be sent without waiting to combine them into larger packets, which reduces the latency or delay for these types of interactive applications.
This is the correct option to reduce packet delay in Telnet and SSH applications.

C. enable Proxy Maximum Segment:

This setting refers to Maximum Segment Size (MSS), which determines the largest segment of data that can be sent in a TCP packet. While adjusting MSS can have an effect on how efficiently data is transmitted over the network, enabling or adjusting the Proxy MSS would not directly address the cause of packet delay in Telnet and SSH applications.

D. increase Maximum Segment Retransmissions:

The Maximum Segment Retransmissions setting controls how many times a TCP segment will be retransmitted if the initial attempt fails. Increasing this value can help improve reliability in case of packet loss but would not address the delay caused by TCP flow control or packet sizing. In fact, increasing retransmissions might lead to further delays if network conditions are poor.

The most effective way to reduce packet delay in Telnet and SSH applications is by disabling Nagle's Algorithm (B). This allows for immediate transmission of small packets, improving the responsiveness of interactive sessions such as Telnet and SSH.

Therefore, the correct answer is B.

Question 3

An LTM device is currently load balancing SIP traffic, but an LTM Specialist notices that SIP requests are frequently being directed to the same server as the initial connection.

What UDP profile setting adjustment would help distribute the SIP traffic more evenly across the servers?

A. Enable Datagram LB
B. Disable Datagram LB
C. Set Timeout to Indefinite
D. Set Timeout to Immediate

Correct Answer: A

Explanation:

In F5 BIG-IP Local Traffic Manager (LTM), when handling protocols like SIP (Session Initiation Protocol) over UDP, proper load distribution requires careful configuration of the UDP profile settings. By default, F5 treats incoming UDP traffic based on flow-based persistence, meaning that repeated messages from the same source and destination IP and port pairs may be consistently directed to the same pool member (server). This behavior can lead to uneven distribution when multiple SIP requests originate from the same client.

To change this behavior and allow for better load distribution, the setting called "Datagram LB" in the UDP profile becomes crucial. When "Datagram LB" is enabled, the LTM device performs load balancing on a per-datagram basis, rather than maintaining a pseudo-session across multiple datagrams. This means that each individual SIP request is evaluated independently, allowing the load balancer to choose a different server for each one, depending on current load balancing algorithms and health status.

When this setting is disabled (the default), the system maintains flow affinity, meaning the same client may consistently hit the same backend server even for distinct SIP requests. In scenarios where SIP clients send frequent and independent requests, disabling Datagram LB leads to stickiness, which is not desirable if even traffic distribution is the goal.

Let’s examine the incorrect options:

Option B, disabling Datagram LB, is the opposite of what is needed. This retains flow affinity and contributes to the very issue the question highlights—SIP traffic repeatedly being sent to the same server.

Option C, setting the timeout to “Indefinite,” affects how long a flow entry remains in the connection table, but it doesn’t directly impact the load balancing behavior or the distribution logic of SIP requests. Keeping timeout indefinite could even worsen stickiness since the system keeps the connection alive longer.

Option D, setting timeout to “Immediate,” would cause flows to age out quickly, possibly reducing stickiness. However, this can lead to unintended side effects such as unnecessary overhead or misrouting of in-flight packets. It’s not the recommended solution for balancing SIP traffic.

Therefore, enabling Datagram LB directly addresses the issue described: the uneven distribution of SIP requests due to flow persistence. With Datagram LB turned on, each UDP packet (or datagram) is treated as an independent transaction, and can be load balanced independently.

The best way to ensure SIP requests are more evenly distributed across servers in this scenario is to enable Datagram LB in the UDP profile.

The correct answer is A.

Question 4

Internet users connecting to a virtual server to download files are encountering latency of around 150 milliseconds but no packet loss.

Which built-in client-side TCP profile should be used to maximize throughput in this scenario?

A. tcp
B. tcp-legacy
C. tcp-lan-optimized
D. tcp-wan-optimized

Correct answer: D

Explanation:

When configuring BIG-IP systems for optimal performance, selecting the correct TCP profile is crucial. Different profiles are designed for different network conditions such as latency, packet loss, and bandwidth. In this case, users are connecting over the Internet and experiencing a latency of 150 ms, with no packet loss, which is typical of wide area network (WAN) conditions.

The tcp-wan-optimized profile is specifically built for WAN scenarios. It is designed to enhance performance in environments with high latency and/or moderate packet loss, although it also performs well even if packet loss is not present, as long as latency is significant.

The key characteristics of the tcp-wan-optimized profile include:

Larger initial congestion window: This allows more data to be sent at the start of the connection, improving throughput.
Delayed acknowledgments (ACKs) are managed more aggressively, helping the sender to ramp up the data transmission rate more quickly.
Increased buffer sizes: This is essential for maintaining throughput in high-latency environments where the bandwidth-delay product is high.
Selective Acknowledgment (SACK) and Window Scaling are enabled, which help maintain performance over longer round-trip times.

Now, consider why the other profiles are less suitable:

Option A: tcp
This is the default TCP profile on the BIG-IP system. It provides a balanced configuration suitable for general use but lacks the specific optimizations needed for high-latency WAN connections. Throughput will be suboptimal in a 150 ms latency scenario.
Option B: tcp-legacy
This profile exists for backward compatibility and does not include modern TCP features like SACK or window scaling. It is not optimized for high-latency environments and offers poorer performance than the tcp or optimized profiles.
Option C: tcp-lan-optimized
This profile is meant for low-latency, high-bandwidth environments like local area networks (LANs). It has aggressive settings for fast ramp-up and throughput in low-delay networks, but it performs poorly in WAN situations due to lack of optimizations for latency. It assumes very low round-trip times and minimal delay.
Option D: tcp-wan-optimized
This is the most appropriate choice for the given scenario. With 150 ms latency and no packet loss, the optimizations it offers will provide the highest possible throughput for clients downloading files over a WAN connection such as the Internet.

In summary, in any environment with high latency—even without packet loss—tcp-wan-optimized delivers better throughput than other profiles because it is tailored to handle the delay efficiently. It ensures that the connection makes the best use of available bandwidth despite the round-trip time.

Correct answer: D

Question 5

Windows PC clients are connecting to a virtual server over a high-speed, low-latency network with no packet loss.

Which built-in client-side TCP profile provides the highest throughput for HTTP downloads?

A. tcp
B. tcp-legacy
C. tcp-lan-optimized
D. tcp-wan-optimized

Correct answer: C

Explanation:

In a scenario where Windows PC clients are connecting over a high-speed, low-latency network with no packet loss, the main concern is optimizing the TCP profile to achieve maximum throughput, particularly for HTTP downloads.

Let’s review each option to see which one would be the best fit for this specific environment:

A. tcp:

The tcp profile is the standard TCP profile, which is designed to work in general-purpose environments. It is the default profile used for most connections but is not specifically optimized for either local area networks (LANs) or wide area networks (WANs). This profile doesn't focus on achieving the highest throughput in specific conditions like low-latency, high-speed networks.

B. tcp-legacy:

The tcp-legacy profile is designed for older environments or for compatibility with legacy systems that may not support newer optimizations. It is less likely to provide the best throughput in modern high-speed, low-latency environments, especially for HTTP downloads.

C. tcp-lan-optimized:

The tcp-lan-optimized profile is specifically designed to optimize TCP traffic for LAN environments (i.e., high-speed, low-latency, and typically with no packet loss). This profile is ideal for maximizing throughput on a high-speed, low-latency network, which is exactly the scenario described in the question.
The optimizations in this profile are tailored for environments where the network does not introduce significant delays or loss, ensuring that HTTP downloads experience the highest throughput.

D. tcp-wan-optimized:

The tcp-wan-optimized profile is tailored for WAN environments where higher latency and potential packet loss are common. It includes settings that can help recover from packet loss and manage delays effectively. While this profile can improve throughput in high-latency or lossy environments, it is not the best choice for a high-speed, low-latency network like the one described in the scenario.

Since the network in the question is described as high-speed, low-latency, and without packet loss, the tcp-lan-optimized profile (C) is the best choice. This profile is specifically designed to maximize throughput in environments like the one described.

Therefore, the correct answer is C.

Question 6

Users are experiencing slow download speeds when retrieving large files over a high-speed WAN connection, and significant packet loss has been detected, though it cannot be resolved. To address the performance degradation caused by this packet loss,

Which two TCP profile settings should be adjusted?

A. slow start
B. proxy options
C. proxy buffer low
D. proxy buffer high
E. Nagle's algorithm

Correct Answers: C and D

Explanation:

In environments with high-speed WAN links and unavoidable packet loss, TCP performance can suffer significantly. Transmission Control Protocol (TCP) is inherently sensitive to packet loss, interpreting it as a sign of congestion, which causes it to reduce its transmission rate. This results in lower throughput, especially when transferring large files. In such scenarios, adjusting the TCP profile settings on devices like an F5 LTM can help mitigate the performance issues.

The two most relevant settings in this case are proxy buffer low and proxy buffer high, which control how much memory is allocated to buffer TCP data between the client and the server. These settings are particularly useful in asymmetric networks, such as high-speed WANs, where the client's and server's network characteristics differ significantly.

Proxy buffer high sets the maximum amount of data that can be buffered by the proxy before it pauses reading from the server. Increasing this value allows the proxy to handle more incoming data before applying backpressure, which is helpful in environments where the client may not be able to read data fast enough due to packet loss.

Proxy buffer low sets the minimum threshold below which the proxy resumes reading data from the server. Raising this value ensures the buffer doesn't drain too quickly, helping to smooth out throughput by maintaining a more consistent flow of data. Together, these two parameters help manage data flow and buffer utilization more effectively, compensating for TCP's performance degradation due to packet loss.

Now let's consider why the other options are less suitable:

Option A (slow start) is a congestion control mechanism that gradually increases the transmission rate of TCP connections. Disabling or modifying slow start might slightly influence performance, but it doesn't directly address buffer capacity or help with sustained throughput over lossy connections. It’s not the most targeted adjustment for this scenario.

Option B (proxy options) is a general category within the TCP profile that includes settings like proxy buffering and handling of client-side versus server-side TCP flows. However, it's too broad and not directly tied to buffering performance under packet loss conditions.

Option E (Nagle's algorithm) is intended to reduce the number of small packets sent over the network by waiting to batch data. Disabling Nagle's algorithm can sometimes help interactive applications or those that send small frequent messages, but it typically does not have a major impact on large file transfers over a WAN. In fact, for bulk data transfers, Nagle’s algorithm often remains irrelevant.

In summary, adjusting proxy buffer low and proxy buffer high allows the system to better handle packet loss by controlling how much data is buffered between the client and server, ensuring smoother throughput on high-latency or lossy WAN links.

The correct answers are C and D.

Question 7

An LTM Specialist is managing an LTM device that has 10 virtual servers set up for the same domain but with different services (such as www.example.com, ftp.example.com, ssh.example.com, and ftps.example.com), each using its own key/certificate pair.

What is the best approach to reduce the number of objects on the LTM device?

A. create a 0 port virtual server and have it answer for all protocols
B. create a 0.0.0.0:0 virtual server thus eliminating all virtual servers
C. create a transparent virtual server thus eliminating all virtual servers
D. create a wildcard certificate and use it on all *.example.com virtual servers

Correct answer: D

Explanation:

The scenario involves managing multiple virtual servers that are essentially tied to the same domain (example.com) but for different subdomains and protocols. Each of these virtual servers currently uses its own SSL/TLS certificate and private key. This creates a large number of configuration objects on the device, which can be inefficient and harder to manage.

To address this, the best and most practical approach is to reduce redundancy in SSL certificates and keys across those virtual servers. This can be accomplished by using a wildcard certificate, which is a certificate that can be used for multiple subdomains of a single domain. For instance, a wildcard certificate for *.example.com would be valid for:

www.example.com
ftp.example.com
ssh.example.com
ftps.example.com
and any other subdomain of example.com

By deploying a wildcard certificate, you eliminate the need to maintain separate SSL certificates and keys for each subdomain. This significantly reduces the number of SSL-related configuration objects on the LTM device, including the number of certificate files, key files, and SSL profiles required.

Why the other options are incorrect:

Option A: create a 0 port virtual server and have it answer for all protocols
A 0 port virtual server (i.e., wildcard port) cannot appropriately distinguish between the different application protocols (HTTP, FTP, SSH, etc.), each of which operates on a different port and may have different behaviors or requirements. This option lacks protocol specificity and is generally not suited for handling such diverse services securely.
Option B: create a 0.0.0.0:0 virtual server thus eliminating all virtual servers
This would essentially be a catch-all for any destination IP and any port, which is not a secure or practical approach in a production environment. It lacks control and granularity, and also doesn’t address the management of SSL/TLS objects, which is the core concern in this question.
Option C: create a transparent virtual server thus eliminating all virtual servers
Transparent virtual servers are typically used for forwarding traffic without modification, often in bridging or inline inspection scenarios. They are not appropriate for managing different services that require SSL termination and protocol-specific handling.
*Option D: create a wildcard certificate and use it on all .example.com virtual servers
This is the most efficient and correct solution. It directly addresses the goal of reducing object count by unifying the SSL certificates across all relevant virtual servers while still allowing each server to handle different protocols and services correctly.

In summary, using a wildcard certificate is the optimal solution to reduce configuration complexity without sacrificing functionality or security, especially when all the services are subdomains of the same root domain.

Correct answer: D

Question 8

Given the current virtual server configuration, which three objects can be removed without disrupting functionality, assuming the pool members are serving simple static web content?

A. tcp
B. http
C. oneconnect
D. snat automap
E. httpcompression

Correct answer: C, D, E

Explanation:

In this configuration, the virtual server is configured to serve static web content using HTTP on port 80. The goal is to determine which settings are unnecessary for serving static content and can be removed without disrupting functionality. Let's go through each option to see how they impact the virtual server's functionality.

A. tcp:

The tcp profile is necessary for controlling TCP-level settings like timeouts, window sizes, and other connection-specific parameters. This profile is often essential for maintaining proper TCP connections, especially for reliable transmission of web traffic, even in static content scenarios.
Therefore, the tcp profile should not be removed.

B. http:

The http profile is crucial for serving web traffic. It handles the HTTP protocol, which is necessary for serving static web content. Without it, the virtual server wouldn't be able to understand or process HTTP requests properly.
Therefore, the http profile cannot be removed.

C. oneconnect:

The oneconnect profile is used to optimize the use of TCP connections by reusing existing connections for multiple client requests. While it can improve performance for high-traffic sites, it is not strictly necessary for serving simple static content. Removing it would not disrupt the functionality of serving static web content.
Therefore, the oneconnect profile can be safely removed.

D. snat automap:

The snat automap setting automatically selects the source IP address for outgoing traffic based on the client's IP. While this setting is useful in some cases, particularly when managing multiple client networks, it is not strictly necessary for serving static content. In some environments, especially when the virtual server is handling only simple HTTP traffic, it can be omitted without affecting functionality.
Therefore, the snat automap can be removed without disrupting the functionality of the virtual server.

E. httpcompression:

The httpcompression profile is used to compress HTTP responses before sending them to clients. While this can reduce bandwidth usage, it is not required for serving static content. If compression is not desired or necessary, it can be removed without disrupting basic functionality.
Therefore, the httpcompression profile can be removed.

The three objects that can be safely removed without disrupting the functionality of the virtual server are:

C. oneconnect (not required for static content).
D. snat automap (not necessary for simple web serving).
E. httpcompression (optional for static content).

Therefore, the correct answer is C, D, E.

Question 9

An LTM device running BIG-IP version 10.2.0 is being upgraded to version 11.2.0 HF1. The upgrade process was initiated by selecting the uploaded Hotfix and installing it to an unused volume. However, after 10 minutes, the process appears stuck at 0%.

What should the LTM Specialist check to resolve this issue?

A. the selected volume has sufficient space available
B. the base software version exists on the LTM device
C. the LTM device has been restarted into maintenance mode
D. the LTM device has an available Internet connection via the management interface

Correct Answer: B

Explanation:

In the scenario described, the upgrade from BIG-IP v10.2.0 to v11.2.0 HF1 is failing to progress, and the LTM Specialist observes that the process is stalled at 0%. One of the most common reasons for this behavior during a hotfix installation is the absence of the required base version of the BIG-IP software on the target volume.

Hotfixes in the BIG-IP ecosystem are not standalone installers. They are designed to be applied on top of an already installed base version. In this case, version 11.2.0 HF1 is a hotfix that must be layered over the corresponding base version 11.2.0. If the base image is not present on the target volume, the system cannot proceed with the installation of the hotfix, and the process appears stuck or halted, typically at 0%.

Let’s examine why the other options are incorrect or less relevant in this scenario:

Option A refers to checking the available space on the selected volume. While it is important to have sufficient space when performing any installation, the upgrade process would usually alert the user to space issues, and the process would not appear stalled at 0%. The system also typically prevents installation attempts to a volume lacking sufficient space.

Option C mentions restarting the device into maintenance mode. Maintenance mode is not a requirement for installing upgrades or hotfixes on BIG-IP systems. The GUI or TMSH typically handles the upgrade process directly, and this step would not be applicable in this context.

Option D suggests verifying the LTM device's Internet connection. However, the hotfix was already uploaded to the device, indicating that an Internet connection is not required at this point. The installation is local and does not depend on external access unless the system is set to automatically download updates, which is not indicated in the scenario.

Therefore, when an upgrade process is stuck at 0%, and a hotfix is involved, the first and most likely cause to investigate is whether the required base software version has been installed on the target volume. If the base version is missing, the hotfix installer will not proceed.

The correct answer is B.

Question 10

An LTM Specialist is preparing to convert a stand-alone BIG-IP LTM device, which is currently in production and configured with several VLANs and floating IPs, into part of an active/standby pair by pairing it with a second device. The proper Device Service Clustering (DSC) settings are already configured on both devices.

To avoid errors during the first configuration sync, which two types of configurations must be manually created or matched on the second device before synchronization? (Choose two.)

A. pools
B. VLANs
C. default route
D. self IP addresses

Correct answers: B and D

Explanation:

When converting a stand-alone BIG-IP LTM device into an HA (high availability) pair using Device Service Clustering (DSC), certain configurations must exist identically on both devices before performing the first full configuration sync. This is because not all configurations are automatically synchronized between devices. Some elements are considered "device-specific" and must be manually created or matched on each unit before synchronization occurs.

Two such critical configuration types are VLANs and self IP addresses.

Let’s look at each of the options in detail:

B. VLANs:
VLANs are considered device-specific configurations. The system will not automatically sync VLAN configurations across devices because each device may be connected to different physical network interfaces. If VLANs are not manually created with the same names and settings on the second device, synchronization attempts may fail with errors about missing or mismatched VLANs. Therefore, VLANs must be configured on the second device before syncing.

D. Self IP addresses:
Similar to VLANs, self IP addresses are also device-specific and are not synchronized through DSC. Both non-floating self IPs (unique to each device) and floating self IPs (shared between active/standby devices) must be carefully configured on the second device. If these are not preconfigured correctly, the synchronization process will likely generate errors about missing IPs, or worse, create inconsistencies that affect traffic handling in failover scenarios.

Now, consider why the other options are incorrect:

A. Pools:
Pools are not considered device-specific; they are part of the configuration objects that do get synchronized across devices. When you perform a sync, the configuration of pools, pool members, and their health monitors are automatically copied to the peer device. There is no need to preconfigure these on the second device.

C. Default route:
The default route is part of the route table, which is shared during configuration sync unless specifically excluded. In most common configurations, this route is included in the synchronized data, and does not require manual configuration prior to sync. However, if route domains or other more advanced networking setups are used, this might be revisited, but it is not typically required for basic first-time sync preparations.

In summary, to prevent synchronization errors during the initial sync process between two BIG-IP LTM devices forming a new HA pair, the second device must have the VLANs and self IP addresses manually created and matched to those on the original device. This ensures that device-specific settings are aligned and that configuration syncs proceed without conflicts.

Correct answers: B and D