Free Access to VMware.3V0-25.25.v2026-08-16.q20 with Valid Practice Test (Page 2)

Question 1

An administrator is troubleshooting why workloads in NSX cannot reach the external network 10.100.0.0/16.
The Tier-0 Gateway is in Active/Active mode and has the following configuration:
* Uplink-1 (VLAN 100): 192.168.100.0/24 -> router R1 at 192.168.100.1
* Uplink-2 (VLAN 101): 192.168.101.0/24 -> router R2 at 192.168.101.1
* A static route for 10.100.0.0/16 was added with both next-hops (192.168.100.1 and 192.168.101.1).
* The Scope of this route is set to Uplink-1.
Symptoms:
* Virtual Machines (VMs) cannot reach 10.100.0.0/16
* Traceroute from the VM stops at the Tier-0 gateway with "Destination Net Unreachable"
* Pings from the Edge nodes to both 192.168.100.1 and 192.168.101.1 are success What explains why workloads in NSX cannot reach the external network?

A.Static routes do not support Equal Cost Multi-Pathing (ECMP) in NSX.
B.The static route Scope is set to only one uplink interface, but the next-hops are on two different VLANs.
C.The next-hops should have been configured as the Tier-0's own uplink IPs instead of the routers IPs.
D.The physical routers are missing return routes.

Correct Answer: B

Comprehensive and Detailed 250 to 350 words of Explanation From VMware Cloud Foundation (VCF) documents:
Troubleshooting routing in a VMware Cloud Foundation (VCF) environment requires a deep understanding of how theNSX Tier-0 Gatewayprocesses forwarding entries. In anActive/Activeconfiguration, the Tier-0 gateway is designed to utilize ECMP (Equal Cost Multi-Pathing) to distribute traffic across multiple paths to the physical network.
The specific failure described-where a traceroute fails at the Tier-0 with "Destination Net Unreachable" despite the Edge nodes having basic ping connectivity to the routers-points toward a routing table entry error rather than a physical connectivity issue. In NSX, when a static route is created, an administrator has the option to set a"Scope."The Scope explicitly tells the NSX routing engine which interface should be used to reach the defined next-hops.
In this scenario, the administrator has defined two next-hops (R1 and R2) but has restricted the scope of the static route toUplink-1 only. Because R2 (192.168.101.1) is on a different subnet/VLAN (VLAN 101) that is associated withUplink-2, the Tier-0 gateway cannot resolve the next-hop for R2 via Uplink-1. Furthermore, if the gateway detects an inconsistency between the defined next-hop and the scoped interface, it may invalidate the route or fail to install it correctly in the forwarding information base (FIB) for the service router.
According to VMware documentation, theScopeshould typically be left as "All Uplinks" or carefully matched to the interfaces that have Layer 2 reachability to the next-hop. By scoping it to only Uplink-1, the router R2 becomes unreachable for that specific route entry. Even for R1, if the hashing mechanism of the Active
/Active Tier-0 attempts to use a component of the gateway not associated with that scope, the traffic will fail.
The error "Destination Net Unreachable" at the Tier-0 hop confirms that the Tier-0 has no valid, functional path in its routing table for the 10.100.0.0/16 network due to this scoping conflict.

Question 2

An administrator is configuring Border Gateway Protocol (BGP) routing on a Tier-0 Gateway to optimize north-south traffic flow between the NSX environment and multiple upstream physical routers. The environment includes two external connections that advertise overlapping routes to the same destination networks. To ensure predictable and efficient routing behavior, the administrator decides to manipulate specific BGP attributes on outbound advertisements and inbound route updates. What are two valid BGP Attributes that can be used to influence the route path traffic will take? (Choose two.)

A.BFD
B.Cost
C.AS-Path Prepend
D.MED

Correct Answer: C,D

Comprehensive and Detailed 250 to 350 words of Explanation From VMware Cloud Foundation (VCF) documents:
In aVMware Cloud Foundation (VCF)architecture, theTier-0 Gatewayis the primary point of integration between the virtualized network and the physical world. When dealing with multiple upstream routers (multi- homing), administrators must influence the BGP path selection process to ensure traffic follows the desired path and avoids suboptimal routing or asymmetric flows.
AS-Path Prependis a common technique used to influenceinbound traffic(traffic coming from the physical network into the NSX environment). By repeating its own Autonomous System (AS) number multiple times in the BGP advertisement, the Tier-0 Gateway makes a specific path look "longer" and therefore less desirable to the upstream physical routers. Since BGP prefers the shortest AS-Path, the routers will favor the alternate link that does not have the prepended AS numbers. This is a critical tool in VCF designs to ensure that a primary link is utilized unless a failure occurs.
MED (Multi-Exit Discriminator)is an attribute that suggests to an adjacent external AS which path to take among multiple entry points to the same AS. Like AS-Path Prepend, it influences inbound traffic. A lower MED value is preferred over a higher one. In a VCF environment with multiple Edge Nodes or multiple Tier-
0 uplinks, setting different MED values allows the administrator to prioritize specific entry points for traffic entering the SDDC.
BFD (Bidirectional Forwarding Detection)is not a BGP attribute; it is a detection protocol used to provide fast failure detection of the link between BGP neighbors. While it triggers faster convergence, it does not influence path selection based on attributes.Costis an OSPF attribute, not a native BGP attribute. Therefore, in the context of NSX Tier-0 BGP configuration, AS-Path Prepend and MED are the verified methods for path manipulation.

Question 3

An administrator is troubleshooting east-west network performance between several virtual machines connected to the same logical segment. The administrator inspects the internal forwarding tables used by ESXi and notices that different tables exist for MAC and IP mapping. Which table on an ESXi host is used to determine the location of a particular workload for frame forwarding?

A.ARP Table
B.FIP Table
C.TEP Table
D.MAC Table

Question 4

An administrator is troubleshooting an issue where workloads connected to a Tier-1 Gateway named T1-App can no longer reach external North/South destinations.
* The Tier-1 is connected to an Active/Standby Tier-0 Gateway named T0-Prod.
Symptoms observed:
* VMs on segments attached to T1-App can ping each other.
* VMs on T1-App cannot reach any external IP outside T0-Prod.
* From a VM on the segment, ping to the T1-App Distributed Router (DR) IP succeeds.
* Ping from the VM to the T1-App Service Router (SR) fails.
* The Edge cluster hosting the T1-App SR shows both Edge nodes Up and Healthy.
* No failover has occurred - the same Edge node is still shown as Active for T1-App.
What is the most likely cause of this issue?

A.The overlay network between DR and SR has an MTU mismatch.
B.Route advertisement from T1-App to T0-Prod for 100.64.x.x/31 is disabled.
C.Static default route is missing on the Tier-1 DR component.
D.Localized control plane is enabled on the Tier-1 causing the SR to remain admin-down.

Question 5

An administrator is troubleshooting BGP flapping in a VMware Cloud Foundation (VCF) 9 environment. A Tier-0 Gateway is running in Active/Active mode with two Edge nodes. BFD is enabled on the eBGP sessions to the upstream routers. Each Edge node uses its own uplink IP for BGP. After some network maintenance, one BGP session starts flapping every few minutes. The other BGP sessions stay stable. On the affected Edge node, the command get bfd-sessions shows:
* State: Down
* Diag: Detect Time Expired
Symptoms:
* The upstream router also shows the BFD session as Down with control Detection Time Expired.
* There are no interface errors, no packet loss for normal traffic, and clearing the BFD session temporarily brings it back up - but it flaps again after few minutes.
What is the root cause?

A.BFD timers are mismatched between Tier-0 Gateway and the upstream routers.
B.The MTU does not match on the end-to-end between Tier-0 Gateway and upstream routers.
C.BFD is configured in echo mode on the upstream routers.
D.The Edge nodes are undersized and are experiencing high contention on CPU and drops BFD packets.

Correct Answer: B

Comprehensive and Detailed 250 to 350 words of Explanation From VMware Cloud Foundation (VCF) documents:
In aVMware Cloud Foundation (VCF)environment, particularly with the high-performance requirements of North-South routing,BGPandBFD (Bidirectional Forwarding Detection)are used in tandem to ensure rapid failure detection. A common but subtle issue in fresh or modified environments is anMTU (Maximum Transmission Unit) mismatchon the physical or virtual uplinks.
When BGP establishes a neighborship, it initially exchanges small keepalive packets. These small packets easily pass through interfaces even if there is an MTU mismatch (e.g., the Edge is set to 9000 bytes but a physical switch in the path is limited to 1500 bytes). However, once the BGP state reaches "Established," the routers begin exchanging full routing tables. TheseBGP Updatepackets are often large and will be fragmented or dropped if they exceed the MTU of any hop in the path.
The symptom described-where the session is stable for a few minutes (during the initial handshake) and then flaps-is the hallmark of an MTU issue. The "Detect Time Expired" diagnostic in BFD occurs because the BGP hold timer expires when it fails to receive the large update packets, or the BFD packets themselves are delayed/lost due to the congestion caused by retrying large, failed transmissions. According to VMware NSX troubleshooting documentation, if pings (small packets) succeed but the BGP session fails specifically when traffic load or route counts increase, the MTU should be the first setting verified.
VCF 9.0 and 5.x designs mandate consistent MTU settings (typically9000 MTUfor the overlay and at least
1500+for the uplinks) across the entire path, including the virtual switch (VDS), the Edge VM vNICs, and the physical ToR switches. A mismatch here prevents the completion of the BGP state machine's full synchronization, leading to the cyclic "flapping" observed by the administrator.

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