300-410 Timed Practice Test 4 — 10 Questions

Question 1

A network engineer runs the following debug command to troubleshoot a DHCPv4 issue on router R1:

R1# debug ip dhcp server events

Output:
 DHCPD: DHCPDISCOVER received from 0050.7966.6800 on interface GigabitEthernet0/0
 DHCPD: Sending DHCPOFFER to 0050.7966.6800 via GigabitEthernet0/0
 DHCPD: DHCPREQUEST received from 0050.7966.6800
 DHCPD: No binding found for client 0050.7966.6800
 DHCPD: Adding binding for client 0050.7966.6800
 DHCPD: Sending DHCPACK to 0050.7966.6800 via GigabitEthernet0/0
 DHCPD: DHCPINFORM received from 0050.7966.6800
 DHCPD: Sending DHCPACK to 0050.7966.6800 via GigabitEthernet0/0

What does this output indicate?

Accepted Answer

The DHCP server successfully assigned an IP address to the client, and the client sent a DHCPINFORM to request additional parameters.. The debug output shows the DHCP server successfully processing a DISCOVER, OFFER, REQUEST, and ACK sequence, followed by an INFORM message. The 'No binding found' message is normal for a new client, and the binding is created. The INFORM is used by the client to obtain additional configuration parameters after the address is assigned.

Answer

The DHCP server failed to create a binding for the client.

Answer

The DHCP client is using a relay agent because the DISCOVER was received on a different interface.

Answer

The DHCP server rejected the DHCPREQUEST because no binding was found.

Question 2

A network engineer is troubleshooting a DHCPv6 prefix delegation issue on router R1 and runs the following command:

R1# debug ipv6 dhcp detail

Output:
 IPv6 DHCP: Received SOLICIT message from FE80::21A:2BFF:FE3C:4D01 on GigabitEthernet0/0
 IPv6 DHCP: Using interface pool DHCP_POOL
 IPv6 DHCP: Sending ADVERTISE message to FE80::21A:2BFF:FE3C:4D01
 IPv6 DHCP: Received REQUEST message from FE80::21A:2BFF:FE3C:4D01
 IPv6 DHCP: Client requests prefix 2001:DB8:1::/48
 IPv6 DHCP: Prefix 2001:DB8:1::/48 not available in pool DHCP_POOL
 IPv6 DHCP: Sending REPLY message with Status Code NoPrefixAvail

What does this output indicate?

Accepted Answer

The DHCPv6 server has a pool configured but the requested prefix is not in that pool or is already allocated.. The debug output shows a DHCPv6 client requesting a specific prefix delegation, but the server's pool does not have that prefix available. The server responds with a NoPrefixAvail status code, indicating the prefix cannot be assigned.

Answer

The DHCPv6 client successfully received the prefix 2001:DB8:1::/48.

Answer

The DHCPv6 client is using a relay agent because the SOLICIT was received on a different interface.

Answer

The DHCPv6 server is configured with a stateless configuration because it sent an ADVERTISE without a prefix.

Question 3

What is the default DHCPv4 client lease time on a Cisco IOS-XE router configured as a DHCP client?

Accepted Answer

86400 seconds (1 day). Cisco IOS-XE defaults to a DHCPv4 lease time of 86400 seconds (1 day) when acting as a client, per RFC 2131 and Cisco implementation.

Answer

3600 seconds (1 hour)

Answer

43200 seconds (12 hours)

Answer

1800 seconds (30 minutes)

Question 4

A network engineer runs the following command to verify DHCPv4 server bindings on router R1:

R1# show ip dhcp binding

Output:
 Bindings from all pools not associated with VRF:
 IP address       Client-ID/              Lease expiration        Type
                   Hardware address/
                   User name
 192.168.1.10     0050.7966.6800           Mar 01 2025 12:00 PM   Automatic
 192.168.1.11     0063.6973.636f.2d30      Mar 01 2025 01:00 PM   Automatic
 192.168.1.12     0100.1a.2b.3c.4d.5e     Mar 01 2025 02:00 PM   Automatic

What does this output indicate?

Accepted Answer

The DHCP server has dynamically assigned three IP addresses to clients.. The show ip dhcp binding command displays active DHCP bindings. The output shows three active leases with IP addresses, client identifiers (MAC addresses or relay-agent IDs), lease expiration times, and the type (Automatic meaning dynamically assigned).

Answer

The DHCP server has three static bindings configured.

Answer

The DHCP server is out of IP addresses because all bindings are in use.

Answer

The DHCP server is using relay agents because the client IDs are long hexadecimal strings.

Question 5

A network engineer runs the following command to troubleshoot DHCPv6 address assignment on router R1:

R1# show ipv6 dhcp binding

Output:
 Client: FE80::21A:2BFF:FE3C:4D01
   DUID: 0003000121A2B3C4D5E6
   Username: unassigned
   VRF: default
   IA NA: IA ID 0x00040001, T1 302400, T2 483840
       Address: 2001:DB8:1::100
           Preferred lifetime 604800, valid lifetime 2592000
           Expires at Mar 01 2025 12:00 PM (2592000 seconds)
   IA PD: IA ID 0x00040002, T1 302400, T2 483840
       Prefix: 2001:DB8:1::/48
           Preferred lifetime 604800, valid lifetime 2592000
           Expires at Mar 01 2025 12:00 PM (2592000 seconds)

What does this output indicate?

Accepted Answer

The DHCPv6 server has assigned both an IPv6 address and a prefix delegation to the client.. The show ipv6 dhcp binding command displays DHCPv6 bindings. This client has both a non-temporary address (IA NA) and a prefix delegation (IA PD). The address 2001:DB8:1::100 and prefix 2001:DB8:1::/48 are assigned with lifetimes.

Answer

The DHCPv6 server has assigned only an IPv6 address to the client.

Answer

The DHCPv6 client is using stateless autoconfiguration (SLAAC) because no address is shown.

Answer

The DHCPv6 server has a pool with only one prefix available.

Question 6

A network engineer runs the following command to verify DHCPv4 server statistics on router R1:

R1# show ip dhcp server statistics

Output:
 Memory usage: 12345
 Address pools: 2
 Database agents: 0
 Automatic bindings: 150
 Manual bindings: 5
 Expired bindings: 10
 Malformed messages: 0

Message    Received
 BOOTREQUEST    0
 DHCPDISCOVER   200
 DHCPREQUEST    180
 DHCPDECLINE    2
 DHCPRELEASE    5
 DHCPINFORM     10

What does this output indicate?

Accepted Answer

The DHCP server has 150 active automatic bindings and 5 manual bindings.. The show ip dhcp server statistics command provides counts of various DHCP messages and bindings. Here, 200 DISCOVERs were received but only 180 REQUESTs, indicating some clients did not proceed after the OFFER. There are 150 automatic bindings and 5 manual (static) bindings.

Answer

The DHCP server has received 200 DHCPREQUEST messages.

Answer

The DHCP server has 10 malformed messages, indicating a configuration issue.

Answer

The DHCP server has 2 database agents configured.

Question 7

An enterprise uses EIGRP for IPv6 with route redistribution from a static route. R1 has a static route 2001:db8:0::/32 via Null0 redistributed into EIGRP. R2 receives this route and has a more specific route 2001:db8:1::/32 via a different interface. R2 has an IPv6 ACL applied inbound on the interface facing R1 that permits only EIGRP and denies all other traffic. R2's uRPF is configured in loose mode. Traffic from R2 to 2001:db8:2::1 fails. R2 shows 'show ipv6 route' has both routes, but 'show ipv6 cef' shows the summary route for 2001:db8:2::1 pointing to R1. What is the root cause?

Accepted Answer

The summary route 2001:db8:0::/32 on R1 points to Null0, causing traffic to be dropped at R1.. The ACL on R2 blocks the data traffic from R2 to the destination because the traffic is sent out the interface facing R1 (due to the summary route), but the ACL is inbound on that interface. However, uRPF loose mode only checks if a route exists in the FIB, not the interface. The issue is that the ACL is blocking the outbound traffic? Actually, the ACL is inbound, so it filters incoming traffic. The traffic from R2 to the destination is outbound, so the ACL does not affect it. The real issue is that the summary route points to R1, but the destination is not reachable via R1 because R1's Null0 route drops it. The ACL is a red herring; the root cause is the summary route causing blackholing.

Answer

The ACL on R2 blocks the return traffic from R1, causing asymmetric routing.

Answer

uRPF loose mode drops the packet because the source address is not in the FIB.

Answer

EIGRP redistribution of the static route creates a routing loop between R1 and R2.

Question 8

A dual-stack network uses BGP for IPv6 between two ISPs. R1 (AS 100) receives a full BGP table from R2 (AS 200). R1 has an IPv6 ACL applied inbound on the interface to R2 that permits only BGP (TCP 179) and denies all other traffic. R1 also has uRPF configured in strict mode on the same interface. R1's BGP table has a route to 2001:db8:1::/48 with next-hop 2001:db8:2::2. R1's routing table shows the route, but traffic from R1 to 2001:db8:1::1 fails. R1 shows 'show ipv6 cef 2001:db8:1::/48' points to 2001:db8:2::2 via the interface to R2. What is the root cause?

Accepted Answer

The ACL on R1 blocks the return traffic from the destination, which is not BGP, causing the ping to fail.. uRPF strict mode checks the source address of outgoing packets? No, it checks incoming packets. For traffic from R1 to the destination, the source is R1's own address. When the return traffic comes back, uRPF checks the source of the return packet. But the issue is that the ACL blocks all traffic except BGP. When R1 sends data to the destination, the return traffic is blocked by the ACL because it is not BGP. The uRPF is not the issue; the ACL is blocking the return traffic.

Answer

uRPF strict mode drops the outgoing traffic because the source address is not reachable via the interface.

Answer

The next-hop 2001:db8:2::2 is not reachable due to a missing ND entry.

Answer

BGP next-hop resolution fails because the next-hop is not in the FIB.

Question 9

A network engineer runs the following command to troubleshoot an IPv6 traffic filtering issue:

R1# show ipv6 access-list FILTER
IPv6 access list FILTER
    permit ipv6 2001:DB8:1::/48 any sequence 10
    deny ipv6 2001:DB8:2::/48 any sequence 20
    permit ipv6 any any sequence 30

What does this output indicate?

Accepted Answer

The access list will permit traffic from 2001:DB8:1::/48 and deny traffic from 2001:DB8:2::/48, but permit all other IPv6 traffic.. The output shows an IPv6 access-list named FILTER with three entries. The first permits traffic from 2001:DB8:1::/48 to any destination. The second denies traffic from 2001:DB8:2::/48. The third permits all other IPv6 traffic. This is a typical filtering configuration.

Answer

The access list will permit traffic from 2001:DB8:1::/48 and deny traffic from 2001:DB8:2::/48, and implicitly deny all other IPv6 traffic.

Answer

The access list will deny all traffic because of the deny statement.

Answer

The access list is invalid because IPv6 access lists require implicit deny at the end.

Question 10

A network engineer runs the following command to verify IPv6 uRPF operation:

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

What does this output indicate?

Accepted Answer

Strict uRPF is enabled, so the router will drop packets if the source address is not in the routing table or if the best return path is not through the receiving interface.. The output shows that strict uRPF (unicast Reverse Path Forwarding) is enabled on interface GigabitEthernet0/0. This means the router will check that the source address of incoming IPv6 packets is reachable via the same interface on which the packet arrived.

Answer

Strict uRPF is enabled, but it only checks if the source address is in the routing table, regardless of interface.

Answer

Loose uRPF is enabled, which only checks if the source address is in the routing table.

Answer

uRPF is disabled on this interface.