350-501 Practice Test 45 — 15 Questions

Question 1

In OSPF Traffic Engineering (TE) extensions for RSVP-TE, which LSA type is used to carry TE information?

Accepted Answer

Type 10 LSA. Opaque LSA Type 10 (area-scoped) is used for OSPF TE, containing sub-TLVs for link attributes.

Answer

Type 5 LSA

Answer

Type 11 LSA

Answer

Type 9 LSA

Question 2

Which OSPF area type can import external routes as Type 7 LSAs?

Accepted Answer

NSSA. NSSA (Not-So-Stubby Area) allows the import of external routes as Type 7 LSAs, which are translated to Type 5 at the ABR.

Answer

Stub area

Answer

Standard area

Answer

Totally stubby

Question 3

An engineer is configuring IS-IS fast convergence. Which mechanism provides sub-second failure detection independently of the routing protocol?

Accepted Answer

BFD. BFD (Bidirectional Forwarding Detection) provides fast failure detection at the link layer, triggering routing protocol convergence.

Answer

LSP fast flooding

Answer

PRC (Partial Route Computation)

Answer

iSPF (incremental SPF)

Question 4

A service provider is implementing 6PE to carry IPv6 traffic over an existing MPLS IPv4 core. Which BGP extension is required on the provider edge (PE) routers to exchange IPv6 prefixes with an IPv4 next-hop?

Accepted Answer

MP-BGP for the IPv6 address family with an IPv4 next-hop encoded in the MP_REACH_NLRI. 6PE uses BGP multiprotocol extensions (MP-BGP) with the IPv6 Address Family Identifier (AFI) and subsequent AFI (SAFI) to carry IPv6 prefixes. The next-hop is encoded as an IPv4 address using the 'next-hop' attribute with an IPv4 address. This is done via MP_REACH_NLRI for IPv6 with an IPv4 next-hop.

Answer

BGP IPv6 unicast address family with IPv6 next-hop

Answer

BGP IPv4 unicast address family with the IPv6 prefix as a label

Answer

BGP VPNv4 address family

Question 5

In an OSPF network, an engineer wants to reduce the size of the routing table and prevent external routes from being advertised into an area. Which area type should be configured?

Accepted Answer

Stub area. A stub area does not allow AS-external LSAs (type 5), reducing routing table size. NSSA allows limited external routes via type 7 LSAs.

Answer

Totally stubby area

Answer

Backbone Area 0

Answer

NSSA

Question 6

In OSPFv3, what change was introduced compared to OSPFv2 for supporting IPv6?

Accepted Answer

OSPFv3 runs over IPv6 and uses link-local addresses for adjacencies. OSPFv3 runs per-link instead of per-subnet, uses link-local addresses for neighbor discovery, and separates the protocol from addressing by using LSAs with IPv6 prefix information.

Answer

OSPFv3 uses the same LSA types as OSPFv2

Answer

OSPFv3 supports only point-to-point network types

Answer

OSPFv3 eliminates the need for a router ID

Question 7

Which BGP community is used to prevent a route from being advertised to any eBGP peers?

Accepted Answer

NO_EXPORT. The well-known community NO_EXPORT (0xFFFFFF01) prevents a route from being advertised to any eBGP peers. The route can still be advertised within the AS.

Answer

INTERNET

Answer

LOCAL_AS

Answer

NO_ADVERTISE

Question 8

A service provider is migrating from a legacy MPLS network using LDP to Segment Routing (SR-MPLS). They have enabled SR on all routers and are using IS-IS. The migration plan is to keep LDP running alongside SR during the transition. After enabling SR, some traffic is being forwarded using the SR path, but the network operator notices that some CEs in an L2VPN are experiencing packet loss during failover scenarios. Troubleshooting shows that the primary pseudowire is using SR labels, but the backup pseudowire is still using LDP labels. The backup path is not working correctly. What is the most likely cause?

Accepted Answer

The backup pseudowire is still using LDP labels and the LDP session for the backup path is down. During coexistence of LDP and SR, there might be a mismatch in label switching. The backup pseudowire might be using LDP labels that are not consistent with the SR forwarding plane. The most likely cause is that the backup path is not properly programmed to use SR labels, or the LDP session for the backup path is down. The correct action is to ensure that the pseudowire's backup signaling is using the same transport mechanisms as the primary, or to disable LDP gradually.

Answer

The backup path uses a different IGP metric

Answer

The MTU on the backup path is smaller than on the primary

Answer

The prefix-SID for the remote PE is missing in the SR-TE database

Question 9

Which access technology is based on ITU-T G.984 and provides downstream speeds up to 2.488 Gbps?

Accepted Answer

GPON. GPON (Gigabit-PON) is defined by ITU-T G.984 with downstream up to 2.488 Gbps.

Answer

XGS-PON

Answer

DSL

Answer

EPON

Question 10

Which THREE are benefits of implementing MPLS-TE in a service provider core?

Accepted Answer

Ability to guarantee bandwidth for specific traffic flows. MPLS-TE allows operators to reserve bandwidth along explicit paths using RSVP-TE signaling, ensuring that specific traffic flows receive guaranteed bandwidth. This is achieved through bandwidth reservation and admission control, which prevents oversubscription on TE tunnels.

Answer

Reduction in BGP routing table size

Answer

Native support for multicast

Question 11

Which THREE are mechanisms used in EVPN to support multi-homing and load balancing? (Choose three.)

Accepted Answer

Aliasing. ESI identifies the segment, DF election avoids duplicates, and aliasing allows traffic to be forwarded to any PE in the multi-homing group.

Answer

Spanning Tree Protocol (STP)

Answer

Virtual Router Redundancy Protocol (VRRP)

Question 12

A service provider operates a large MPLS network with Segment Routing (SR) and BGP-LS enabled on all routers. They have deployed a centralized Path Computation Element (PCE) to compute SR-TE policies for optimal traffic engineering. The PCE is configured to receive the network topology via BGP-LS from a route reflector (RR). Recently, the PCE has been unable to compute paths for certain destinations, and logs show that the topology database is missing some links and nodes. The engineer verifies that all routers have BGP-LS configured and are peering with the RR. The RR's BGP table shows the BGP-LS NLRI received from all routers. However, the PCE sees only a subset of the topology. Which action should the engineer take to resolve the issue?

Accepted Answer

Configure the RR to send BGP-LS routes to the PCE. Verify that the RR has a BGP session with the PCE in the address-family link-state.. The PCE is not receiving the full topology because the Route Reflector (RR) is not sending BGP-LS routes to the PCE. The most likely cause is that the RR is not configured to advertise BGP-LS to the PCE. Option C is correct: the engineer should verify that the RR has a BGP session with the PCE in the address-family link-state and ensure that BGP-LS routes are being sent. Option A is wrong because BGP-LS relies on IGP for link-state information, but the issue is not with IGP visibility; the RR already receives BGP-LS from all routers. Option B is wrong because filtering out prefixes would reduce topology information, not solve missing data. Option D is wrong because the PCE does not need direct BGP-LS adjacency to each router; it can receive topology via the RR.

Answer

Check the IGP (OSPF/IS-IS) configuration on the routers. BGP-LS relies on IGP to obtain link-state information, and if IGP does not have full visibility, BGP-LS will not either.

Answer

Apply a prefix-list on the PCE to filter out unwanted BGP-LS prefixes, as the PCE may be overwhelmed.

Answer

Verify that the PCE itself has a BGP-LS adjacency to each router, bypassing the RR.

Question 13

Drag and drop the steps to configure a PPPoE client on a Cisco router into the correct order.

Accepted Answer

Step 1: Create dialer interface, Step 2: Set encapsulation PPP, Step 3: Configure dialer pool, Step 4: Set authentication (PAP/CHAP), Step 5: Assign IP address negotiated. PPPoE client configuration involves creating a dialer interface, setting encapsulation, dialer pool, authentication, and IP address.

Answer

Step 1: Create dialer interface, Step 2: Set encapsulation PPP, Step 3: Set authentication, Step 4: Configure dialer pool, Step 5: Assign IP address

Answer

Step 1: Configure dialer pool, Step 2: Create dialer interface, Step 3: Set encapsulation PPP, Step 4: Set authentication, Step 5: Assign IP address

Answer

Step 1: Create dialer interface, Step 2: Set encapsulation PPP, Step 3: Assign IP address, Step 4: Configure dialer pool, Step 5: Set authentication

Question 14

Drag and drop the steps to configure a standard ACL on a Cisco router into the correct order.

Accepted Answer

Enter global configuration mode, then create the standard access list, then enter interface configuration mode, then apply the access list to the interface.. Standard ACL configuration requires creating the ACL and applying it to an interface in the appropriate direction.

Answer

Enter global configuration mode, then enter interface configuration mode, then create the standard access list, then apply the access list to the interface.

Answer

Create the standard access list, then enter global configuration mode, then enter interface configuration mode, then apply the access list to the interface.

Answer

Enter global configuration mode, then create the standard access list, then apply the access list to the interface, then enter interface configuration mode.

Question 15

A network engineer applies the above configuration on a PE router. The PE receives route 172.16.1.0/24 from eBGP peer 10.1.1.1. Which communities will be attached to this route?

Accepted Answer

65000:100 and 65000:200. The route-map 'SET_COMMUNITY' is applied to the eBGP neighbor 10.1.1.1 via the `neighbor 10.1.1.1 route-map SET_COMMUNITY in` command. The route-map first matches all routes with `match ip address prefix-list ANY` (which permits 0.0.0.0/0 le 32), then executes the `set community 65000:100 65000:200` action. Since the `additive` keyword is not used, the set command replaces any existing communities with the two listed communities (65000:100 and 65000:200). Therefore, both communities are attached to the route 172.16.1.0/24.

Answer

65000:100 only

Answer

No communities are attached because the route-map does not specify additive.

Answer

65000:200 only