350-501 Networking Practice Test 2 — 15 Questions

Question 1

An engineer is configuring IS-IS in a service provider network. The network uses wide metrics for traffic engineering. Which TLV is mandatory for IS-IS to carry traffic engineering (TE) information in accordance with RFC 5305?

Accepted Answer

TLV 22 (Extended IS Reachability). TLV 22 (Extended IS Reachability) is the mandatory TLV for IS-IS TE, defined in RFC 5305.

Answer

TLV 135 (Extended IP Reachability)

Answer

TLV 229 (Multi-Topology Reachable IPv4 Prefixes)

Answer

TLV 128 (IP Internal Reachability)

Question 2

In an IS-IS network, a router has a NET of 49.0001.1921.6800.1001.00. What does the '00' at the end represent?

Accepted Answer

SEL (NSAP Selector). The last byte '00' is the SEL (NSAP Selector), which is always '00' for IS-IS routing.

Answer

System ID

Answer

AFI

Answer

Area ID

Question 3

A service provider is deploying OSPFv3 for IPv6 in its core. The network uses multiple areas. Which LSA type is used by OSPFv3 to advertise prefix information for inter-area routes?

Accepted Answer

Inter-Area Prefix LSA (Type 0x2003). In OSPFv3, Inter-Area Prefix LSAs (Type 0x2003) are used to advertise prefixes from other areas.

Answer

Network LSA (Type 0x2002)

Answer

Intra-Area Prefix LSA (Type 0x2009)

Answer

Router LSA (Type 0x2001)

Question 4

An ISP is implementing BGP PIC (Prefix Independent Convergence) for edge routers. Which BGP feature must be enabled to support PIC for core-facing failures?

Accepted Answer

BGP additional-paths install. BGP PIC relies on installing a backup path in the FIB. For core-facing failures, BGP Fast External Fallover and BGP PIC with backup paths are used; specifically, 'bgp additional-paths install' is needed to install backup paths.

Answer

BGP deterministic-med

Answer

BGP route refresh

Answer

BGP bestpath as-path multipath-relax

Question 5

Which BGP attribute is used to prefer a specific entry point into an AS when multiple ASBRs are advertising the same prefix to a neighboring AS?

Accepted Answer

MED. MED (Multi-Exit Discriminator) is used to influence the inbound traffic by suggesting the preferred entry point.

Answer

LOCAL_PREF

Answer

WEIGHT

Answer

AS_PATH

Question 6

Which OSPF network type elects a Designated Router (DR) and Backup Designated Router (BDR) to reduce the number of adjacencies on a multi-access segment?

Accepted Answer

Broadcast. Broadcast network type uses DR/BDR election. Point-to-point and NBMA do not elect DR/BDR (NBMA does elect DR/BDR but is less common).

Answer

Point-to-point

Answer

Loopback

Answer

Point-to-multipoint

Question 7

An SP is designing an OSPF network with a totally stubby area to reduce the LSA database. Which LSA types are blocked by default in a totally stubby area?

Accepted Answer

Type 3, Type 4, and Type 5. Totally stubby area blocks Type 4 (ASBR Summary) and Type 5 (External) LSAs, and also Type 3 (Summary) LSAs except for the default route.

Answer

Type 3 and Type 5 only

Answer

Type 5 only

Answer

Type 4 and Type 5 only

Question 8

In IS-IS, what is the result of configuring wide metrics on all interfaces?

Accepted Answer

Higher metric values are supported for traffic engineering. Wide metrics (24-bit or 32-bit) allow values up to 16,777,215 or higher, enabling TE and faster convergence with precise metric adjustments.

Answer

Only L2 routers can use wide metrics

Answer

Metrics are limited to 63

Answer

IS-IS TLVs are backward compatible with narrow metrics

Question 9

A service provider is implementing 6VPE to provide IPv6 L3VPN services over an MPLS core. Which BGP address family must be configured on the PE routers to exchange IPv6 VPN routes?

Accepted Answer

VPNv6 unicast. 6VPE uses the VPNv6 address family (or IPv6 labeled unicast with VPN extensions) to carry IPv6 prefixes with VPN-IPv6 addresses.

Answer

IPv6 unicast

Answer

VPNv4 unicast

Answer

IPv4 unicast

Question 10

In BGP, which attribute is used to prevent routing loops when route reflectors are deployed?

Accepted Answer

Originator ID. Originator ID is used by route reflectors to prevent loops. If a router receives a route with its own router ID as originator, it discards it.

Answer

Cluster ID

Answer

AS_PATH

Answer

NEXT_HOP

Question 11

Which BGP attribute is locally significant and used to influence outbound traffic from an AS?

Accepted Answer

LOCAL_PREF. LOCAL_PREF is used to influence the path selection for outbound traffic within the AS, with higher preference preferred.

Answer

WEIGHT

Answer

AS_PATH

Answer

MED

Question 12

An SP is deploying IS-IS fast convergence using Partial Route Computation (PRC). Under which condition does PRC occur?

Accepted Answer

When a prefix is added or removed without topology change. PRC is triggered when a prefix changes but the topology remains unchanged. It recalculates only the affected prefixes, not the entire SPF tree.

Answer

When the IS-IS metric changes

Answer

When the system ID changes

Answer

When a new adjacency is formed

Question 13

A service provider is designing an OSPF network for both IPv4 and IPv6. Which two features are supported by OSPFv3 but not by OSPFv2? (Choose two.)

Accepted Answer

Support for IPv6. OSPFv3 runs over IPv6, supports multiple instances per link, and uses link-local addresses. OSPFv2 does not have these.

Answer

Virtual links

Answer

Authentication using MD5

Answer

Route redistribution

Question 14

Which three BGP attributes are considered in the route selection process before comparing MED? (Choose three.)

Accepted Answer

Weight. The order: weight, local pref, originate (locally originated), AS_PATH length, ORIGIN, MED. So weight, local pref, and AS_PATH length are before MED.

Answer

MED

Answer

Router ID

Question 15

An ISP is implementing 6PE for IPv6 transport over MPLS. Which two conditions are required for 6PE to work? (Choose two.)

Accepted Answer

BGP multiprotocol extensions for IPv6. 6PE requires BGP to carry IPv6 prefixes with an IPv4 next-hop (MPLS label), and the core MPLS network must support IPv4 LSPs.

Answer

IPv6 MPLS LSPs in the core

Answer

IPv6 next-hop in BGP updates

Answer

6PE requires 6VPE