300-410 Practice Test 47 — 15 Questions

Question 1

When redistributing routes between OSPF and EIGRP, which of the following is a recommended best practice to prevent routing loops?

Accepted Answer

Apply route filtering using route-maps or prefix-lists to control which routes are redistributed.. Applying route filtering using route-maps or prefix-lists is a best practice to control which routes are redistributed between OSPF and EIGRP. This prevents routing loops by ensuring that only intended routes are advertised and avoids feedback of routes back into the original protocol. It also allows for granular control over route attributes.

Answer

Use the same administrative distance for both protocols.

Answer

Increase the default metric to a high value to discourage redistribution.

Answer

Disable route summarization on both protocols.

Question 2

A network engineer runs the following command to verify IPv6 uRPF on an interface:

R1# show ipv6 interface GigabitEthernet0/0 | include verify|suppress
  IPv6 verify source: strict
  IPv6 verify source suppress: disabled

What does this output indicate?

Accepted Answer

Strict uRPF is enabled, and no suppression is configured, so all incoming packets are subject to strict verification.. The output shows 'IPv6 verify source: strict' and 'IPv6 verify source suppress: disabled'. This confirms that strict unicast Reverse Path Forwarding (uRPF) is enabled on the interface, meaning every incoming packet's source address is checked against the routing table to ensure the best return route uses the same incoming interface. Because suppression is disabled, no packets bypass this verification, so all incoming packets are subject to strict uRPF checks.

Answer

Loose uRPF is enabled with suppression.

Answer

uRPF is disabled on this interface.

Answer

Suppression is enabled, so uRPF checks are bypassed.

Question 3

What is the default administrative distance for a route learned via the Enhanced Interior Gateway Routing Protocol (EIGRP) summary route?

Accepted Answer

5. EIGRP summary routes have a default administrative distance of 5, which is lower than the standard EIGRP internal distance of 90 and EIGRP external distance of 170.

Answer

90

Answer

170

Answer

1

Question 4

A network engineer runs the following command on Router R1:

R1# show ip nhrp
10.0.0.2/32 via 10.0.0.2, Tunnel0 created 00:15:30, expire 01:44:30
    Type: dynamic, Flags: used
    NBMA address: 192.168.1.2
10.0.0.3/32 via 10.0.0.3, Tunnel0 created 00:10:20, expire 01:49:40
    Type: dynamic, Flags: used
    NBMA address: 192.168.1.3

Based on this output, which statement is correct?

Accepted Answer

Both NHRP entries are active and dynamically learned.. The output shows two NHRP entries with Type: dynamic and Flags: used, indicating they were dynamically learned via NHRP registration/resolution and are currently active (not expired). The expire timers (01:44:30 and 01:49:40) confirm they are valid.

Answer

Both NHRP entries are static.

Answer

The NHRP entries have expired.

Answer

The NBMA addresses are IPv6 addresses.

Question 5

A network engineer is troubleshooting PAT (overload) on a Cisco router. The inside network uses 192.168.1.0/24, and the outside interface has IP 198.51.100.1. The engineer configured 'ip nat inside source list 1 interface GigabitEthernet0/0 overload'. Traffic from inside hosts works initially, but after a few minutes, new connections fail. 'Show ip nat translations' shows many entries with the same outside global IP but different ports. 'Show ip nat statistics' indicates that the number of translations is near 500. What is the most likely cause?

Accepted Answer

The router has run out of available port numbers for PAT.. The router is using PAT (Port Address Translation) with overload, which maps multiple inside local IP addresses to a single outside global IP (198.51.100.1) by using unique source port numbers. With approximately 500 active translations and the router nearing the default limit of around 500 PAT entries (or the available port range of 1024–65535 being exhausted), new connections fail because no unique port numbers are available to assign. This is the classic symptom of PAT port exhaustion.

Answer

The NAT pool is not configured with overload.

Answer

The outside interface is flapping, causing translations to be cleared.

Answer

The access list is denying some inside hosts.

Question 6

A network engineer runs the following command on Router R1:

R1# show policy-map control-plane

Control Plane

Service-policy input: CoPP-IN

Class-map: CoPP-EIGRP (match-all)
      200 packets, 12000 bytes
      5 minute offered rate 1000 bps, drop rate 0000 bps
      Match: access-group 150
      police:
          cir 16000 bps, bc 3000 bytes, be 3000 bytes
        conformed 200 packets, 12000 bytes; actions:
          transmit
        exceeded 0 packets, 0 bytes; actions:
          drop
        violated 0 packets, 0 bytes; actions:
          drop

R1# show ip eigrp neighbors
EIGRP-IPv4 neighbors for process 100
H   Address                 Interface       Hold Uptime    SRTT   RTO  Q  Seq
                                            (sec)         (ms)       Cnt Num
0   10.1.1.2                Gi0/0            13 00:10:00    1   200  0  5

Based on this output, which statement is correct?

Accepted Answer

EIGRP traffic is being rate-limited but no packets are dropped.. The output shows that the CoPP policy 'CoPP-IN' matches EIGRP packets (via access-group 150) and applies a police rate of 16,000 bps. The 'conformed' counter shows 200 packets transmitted, while 'exceeded' and 'violated' counters are zero, indicating no packets have been dropped. The 'show ip eigrp neighbors' output confirms the neighbor is established with an uptime of 10 minutes, so EIGRP traffic is being rate-limited but not dropped, making option B correct.

Answer

EIGRP packets are being dropped, causing neighbor flapping.

Answer

The police rate is set to 8000 bps.

Answer

The EIGRP neighbor is not established.

Question 7

Which DHCPv6 message is used by a server to respond to a SOLICIT with available configuration parameters?

Accepted Answer

ADVERTISE. In DHCPv6, when a client sends a SOLICIT message to discover available DHCPv6 servers, each server that can provide configuration parameters responds with an ADVERTISE message. This ADVERTISE message contains the server's preference and available configuration options, allowing the client to select the appropriate server. This process is defined in RFC 8415 and mirrors the DHCPv4 OFFER step.

Answer

REPLY

Answer

RECONFIGURE

Answer

INFORMATION-REQUEST

Question 8

A router is configured with uRPF (Unicast Reverse Path Forwarding) in strict mode on an interface that belongs to a VRF. The network uses asymmetric routing for load balancing. The engineer notices that legitimate traffic from a customer is being dropped. Which is the most likely explanation?

Accepted Answer

The uRPF strict mode requires that the source IP address be reachable via the same interface, but asymmetric routing causes the return path to use a different interface.. Strict uRPF requires that the router's reverse-path lookup for the packet's source IP resolve out the same interface the packet arrived on. With asymmetric routing, the return path to the customer is via a different interface than the one receiving the traffic, so the strict check fails and the packet is dropped. This is the classic failure mode of strict uRPF in multi-path or load-balanced designs.

Answer

The uRPF loose mode is configured instead of strict mode, which only checks that a route exists for the source IP, not the interface.

Answer

The VRF has a default route that points to the incoming interface, causing uRPF to always succeed.

Answer

The 'ip verify unicast source reachable-via any' command is used, which is the loose mode, not strict.

Question 9

What is the default port number used by syslog servers to receive UDP syslog messages?

Accepted Answer

UDP 514. RFC 5424 and the traditional BSD syslog implementation define UDP port 514 as the standard port for receiving syslog messages. Most network devices and syslog daemons default to sending and listening on UDP 514, making it the correct answer. TCP 514 is used for rsh, not syslog, and UDP 162/161 belong to SNMP.

Answer

UDP 162

Answer

TCP 514

Answer

UDP 161

Question 10

Examine the RSPAN configuration:

vlan 100
 name RSPAN_VLAN
 remote-span
!
monitor session 1 source interface GigabitEthernet1/0/1 both
monitor session 1 destination remote vlan 100

What is the purpose of the 'remote-span' command under VLAN 100?

Accepted Answer

It allows VLAN 100 to be used for RSPAN traffic across multiple switches.. The 'remote-span' command under a VLAN configuration designates that VLAN as an RSPAN VLAN, which is used to carry mirrored traffic across multiple switches in an RSPAN session. This allows the destination port to be on a different switch than the source.

Answer

It enables spanning tree on VLAN 100.

Answer

It prevents VLAN 100 from being used for user data traffic.

Answer

It configures VLAN 100 as a native VLAN.

Question 11

According to Cisco IOS default behavior, if a router learns the same route via both RIP and OSPF, which route will be installed in the routing table?

Accepted Answer

The OSPF route, because OSPF has a lower administrative distance.. Cisco IOS selects routes based on administrative distance (AD) before metric when routes come from different routing protocols. OSPF has a default AD of 110, while RIP has a default AD of 120. Because lower AD is preferred, the OSPF route is installed in the routing table, even if RIP's metric is numerically lower.

Answer

The RIP route, because RIP has a lower metric.

Answer

Both routes are installed, and load balancing occurs.

Answer

Neither route is installed; the router will use a default route.

Question 12

A network engineer configures a DMVPN spoke with the following:

interface Tunnel0
 ip address 10.0.0.3 255.255.255.0
 ip nhrp network-id 100
 ip nhrp nhs 10.0.0.1
 tunnel source GigabitEthernet0/0
 tunnel mode gre multipoint
 ip nhrp map 10.0.0.1 192.168.1.1
 ip nhrp map multicast 192.168.1.1
!

What will happen when the spoke tries to send traffic to another spoke (10.0.0.4)?

Accepted Answer

The spoke will send traffic directly to 10.0.0.4 if it has a cached NHRP mapping, otherwise through the hub.. In DMVPN, a spoke can send traffic directly to another spoke if it has a cached NHRP mapping for that spoke's NBMA address. If no mapping exists, the spoke sends the packet to the hub (NHS), which then redirects it to the destination spoke and may send an NHRP resolution reply to the source spoke. The static multicast map only affects multicast traffic, not unicast. Thus, option A correctly describes the behavior.

Answer

The spoke will always send traffic through the hub because of the static multicast map.

Answer

The spoke will send traffic directly to 10.0.0.4 without using the hub.

Answer

The spoke will drop the traffic because it does not have a route to 10.0.0.4.

Question 13

A network engineer runs the following command to troubleshoot an MPLS Operations issue:

R1# debug mpls ldp transport 10.1.1.1

Output:
*Mar  1 00:01:23.456: LDP: Sent hello to 10.1.1.1 (UDP 646) on GigabitEthernet0/0
*Mar  1 00:01:23.789: LDP: Received hello from 10.1.1.1 (UDP 646) on GigabitEthernet0/0
*Mar  1 00:01:24.012: LDP: Opened TCP connection to 10.1.1.1:646
*Mar  1 00:01:24.345: LDP: Initialization msg sent to 10.1.1.1
*Mar  1 00:01:24.678: LDP: Initialization msg received from 10.1.1.1
*Mar  1 00:01:25.001: LDP: Session with 10.1.1.1:0 (0x1234) is UP

What does this output indicate?

Accepted Answer

LDP session with neighbor 10.1.1.1 is successfully established. The debug output shows the full LDP session establishment sequence: hello exchange over UDP 646, TCP connection to port 646, initialization message exchange, and finally 'Session ... is UP.' This confirms that the LDP session with neighbor 10.1.1.1 has been successfully established.

Answer

LDP discovery via multicast hello failed

Answer

TCP connection to 10.1.1.1 was refused

Answer

LDP session is stuck in initialization state

Question 14

What is the default value of the 'reachable time' in IPv6 Neighbor Discovery (ND) on Cisco IOS-XE?

Accepted Answer

0 milliseconds (unspecified). In IPv6 Neighbor Discovery (ND) on Cisco IOS-XE, the default value for the 'reachable time' is 0 milliseconds (unspecified). This means the router does not advertise a specific reachable time in its Router Advertisements (RAs), leaving the receiving hosts to use their own default value (typically 30,000 milliseconds as per RFC 4861). The 'reachable time' is the duration a node considers a neighbor reachable after confirming reachability via Neighbor Solicitation (NS) or Neighbor Advertisement (NA) messages.

Answer

30,000 milliseconds

Answer

60,000 milliseconds

Answer

10,000 milliseconds

Question 15

When troubleshooting SNMPv3 authentication failures, which default HMAC algorithm is used if the user is configured with "auth md5"?

Accepted Answer

HMAC-MD5-96. When a user is configured with 'auth md5' in SNMPv3, the default HMAC algorithm used is HMAC-MD5-96. This is defined in RFC 3414, which specifies that the authentication protocol 'MD5' actually refers to HMAC-MD5-96, not raw MD5. The HMAC construction provides keyed hashing for message integrity and authentication, and the '-96' indicates that the output is truncated to 96 bits (12 bytes).

Answer

HMAC-SHA-96

Answer

HMAC-SHA-256

Answer

No HMAC is used; MD5 is used directly.