F5CAB3 Sample Questions Answers

Standard DNS queries use UDP. Configuring the Virtual Server for TCP causes DNS traffic to fail.

Forwarding (IP) virtual servers forward traffic based on routing decisions and do not use pools or pool members.

DNS traffic is primarily transported usingUDP port 53. In the exhibit, the Virtual Server is configured with theProtocol set to TCP, which prevents standard DNS queries from being processed correctly. BIG-IP Virtual Servers must be configured with the correct Layer 4 protocol to match the application traffic they are handling.

According to theBIG-IP Administration: Data Plane Configurationdocumentation:

TheProtocolsetting on a Virtual Server defines whether traffic is processed as TCP, UDP, or another supported transport protocol.

Standard DNS queries and responses useUDP, whileTCP is only required for DNS zone transfers (AXFR)or exceptionally large responses.

When a DNS Virtual Server is incorrectly configured with TCP, UDP-based DNS queries are dropped, causing all requests to fail.

Why the other options are incorrect:

A. Protocol profile (Client) to DNS_OPTIMIZEDA DNS profile enhances DNS functionality but does not correct an incorrect transport protocol configuration.

B. Type to Performance (HTTP)Performance (HTTP) Virtual Servers are designed for HTTP traffic and are not suitable for DNS services.

C. Source Address to 192.168.10.0/24The existing source IPs already fall within the allowed range, so this setting does not address the failure.

Correct Resolution:

Changing theProtocol to UDPaligns the Virtual Server with standard DNS transport requirements, allowing DNS queries to be successfully processed and load-balanced.

WAN-optimized TCP profiles improve performance for high-latency Internet clients, while LAN profiles are optimal for backend servers.

Forwarding (IP) virtual servers operate at Layer 3 and forward traffic based on routing, not pools.

The requirement states that load balancing decisions must be based on thenumber of active connections on each pool member. This directly maps to theLeast Connections (member)load balancing method.

According to theBIG-IP Administration: Data Plane Configurationdocumentation:

Least Connections (member)selects the pool member with thefewest active connectionsat the time of the request.

This method dynamically adapts to real-time traffic patterns and ensures that more heavily loaded pool members receive fewer new connections.

It is especially effective for web servers where connection duration may vary and equal distribution of active sessions is desired.

Why the other options are incorrect:

B. Round RobinDistributes connections sequentially without considering current load or active connections.

C. Ratio (member)Distributes traffic based on static ratios, not real-time connection counts.

D. Ratio (node)Uses predefined ratios at the node level and does not account for active connection counts.

Correct Resolution:

UsingLeast Connections (member)ensures that new connections are directed to the pool member currently handling the fewest active connections, meeting the stated requirement.

Performance (Layer 4) virtual servers rely on FastL4 profiles to provide high-speed L4 processing without full proxy overhead.

Below isBATCH 2 (next 10 questions)extractedonlyfrom your uploaded document that areclearly related toBIG-IP Administration: Data Plane Configurationtopics.

❗As requested, I havestrictly excludedquestions related to:

Licensing

HA / Device Trust / Sync-only

Logging destinations

User roles

Hardware, EUD, support processes

System-only administration

Source: Your uploadedTMOS Administration v2.0document

When the connection limit is reached, BIG-IP resets new connections, even if pool members are healthy.

A red diamond indicates the Virtual Server is enabled but unavailable due to all pool members being down.