DHCP (IPv4 and IPv6)

A network engineer is troubleshooting a DHCPv4 issue on a Cisco router configured as a DHCP server. Clients on VLAN 10 are unable to obtain IP addresses. The engineer verifies that the DHCP pool is correctly configured and that the router interface facing the clients has 'ip helper-address 192.168.1.1' pointing to the DHCP server. However, the DHCP server is on a different subnet and the router's interface is in a VRF. The DHCP DISCOVER messages are not reaching the server. What is the most likely cause?

An engineer is troubleshooting an IPv6 deployment where hosts on a subnet are not receiving IPv6 addresses via SLAAC. The router is configured with 'ipv6 unicast-routing' and the interface has 'ipv6 address 2001:db8:1::1/64' and 'ipv6 nd other-config-flag'. The hosts are sending Router Solicitations but receive no Router Advertisements. What is the root cause?

A network engineer is troubleshooting a DHCPv4 relay scenario where clients on subnet 10.1.1.0/24 are unable to obtain IP addresses from a DHCP server at 192.168.1.10. The router interface Gi0/0 (10.1.1.1/24) has 'ip helper-address 192.168.1.10' configured. The engineer captures packets and sees DHCP DISCOVER messages sourced from 10.1.1.1 being sent to 192.168.1.10, but no replies are seen. The server is reachable via ping from the router. What is the most likely cause?

An engineer is troubleshooting a DHCPv6 stateful (DHCPv6) deployment. The router is configured as a DHCPv6 server with a pool for prefix 2001:db8:2::/64. Clients on the LAN are configured to use DHCPv6, but they are not receiving IPv6 addresses. The router interface has 'ipv6 address 2001:db8:2::1/64' and 'ipv6 dhcp server DHCP_POOL'. The engineer sees that the clients are sending SOLICIT messages, but the router sends no REPLY. What is the issue?

A network engineer is troubleshooting a DHCPv4 issue where clients on a subnet are getting IP addresses from the correct pool, but they cannot reach the default gateway. The router is configured as a DHCP server with pool 'POOL' that includes 'default-router 192.168.1.1'. The router's interface IP is 192.168.1.1/24. Clients receive the address and default gateway, but pings to 192.168.1.1 fail. What is the most likely cause?

An engineer is troubleshooting a DHCPv4 issue where a Cisco router acting as a DHCP client on interface Gi0/0 is not receiving an IP address from an ISP modem. The router has 'ip address dhcp' on the interface. The engineer sees that the interface is up/up, but no IP address is assigned. Debug shows that the router is sending DHCP DISCOVER messages but receives no OFFER. The ISP modem is known to work with other devices. What is the most likely cause?

A network engineer is troubleshooting a DHCPv4 issue where a router configured as a DHCP server is not assigning addresses from a pool to clients on a specific VLAN. The pool is configured with 'network 10.1.1.0 255.255.255.0' and 'default-router 10.1.1.1'. The router's interface Gi0/0.10 (subinterface) has encapsulation dot1Q 10 and IP 10.1.1.1/24. Clients send DISCOVER messages, but the router does not respond. The engineer notices that the router has multiple DHCP pools configured. What is the most likely cause?

An engineer is troubleshooting a DHCPv6 prefix delegation scenario. The router (R1) is a DHCPv6 client on its WAN interface and is supposed to receive a /48 prefix from the ISP's DHCPv6 server to delegate to LAN interfaces. The WAN interface is configured with 'ipv6 address dhcp' and 'ipv6 dhcp client pd ISP-PREFIX'. The LAN interfaces have 'ipv6 address ISP-PREFIX 0:0:0:1::/64 eui-64'. The engineer sees that the WAN interface gets a global IPv6 address, but the LAN interfaces do not get any IPv6 address. What is the most likely cause?

A network engineer is troubleshooting a DHCPv4 issue where a router configured as a DHCP server is not assigning addresses to clients on a subnet that is reachable via a different router (relay). The relay router (R2) has 'ip helper-address 10.1.1.1' on its client-facing interface, and the DHCP server is at 10.1.1.1 (R1). The engineer sees that R2 is sending DHCP DISCOVER messages with giaddr set to the client-facing interface IP, but R1 is not responding. R1 has a DHCP pool for the client subnet. The engineer pings 10.1.1.1 from R2 successfully. What is the most likely cause?

A network engineer runs the following command on Router R1: R1# show ip dhcp binding Bindings from all pools not associated with VRF: IP address Client-ID/ Lease expiration Type Hardware address/ User name 192.168.1.10 0063.6973.636f.2e30. Mar 01 2020 12:00 AM Automatic 3030.3030.2e30.3030 312e.3130.3030.2e30 3030.312d.4574.682d 302f.31 192.168.1.11 0063.6973.636f.2e30. Mar 01 2020 12:00 AM Automatic 3030.3030.2e30.3030 312e.3130.3030.2e30 3030.312d.4574.682d 302f.31 Based on this output, which statement is correct?

A network engineer runs the following command on Router R1: R1# show ip dhcp conflict IP address Detection method Detection time VRF 192.168.1.20 Ping Mar 01 2020 01:00 AM 192.168.1.21 Gratuitous ARP Mar 01 2020 01:05 AM Based on this output, what is the problem?

A network engineer runs the following command on Router R1: R1# show ipv6 dhcp binding Client: FE80::A8BB:CCFF:FE01:0200 DUID: 00030001AABBCC010200 Username: unassigned IA NA: IA ID 0x00010001, T1 302400, T2 483840 Address: 2001:DB8:1::1000 Preferred lifetime 604800, valid lifetime 2592000 Expires at Mar 08 2020 12:00 AM (2592000 seconds) Client: FE80::A8BB:CCFF:FE01:0300 DUID: 00030001AABBCC010300 Username: unassigned IA NA: IA ID 0x00010001, T1 302400, T2 483840 Address: 2001:DB8:1::1001 Preferred lifetime 604800, valid lifetime 2592000 Expires at Mar 08 2020 12:00 AM (2592000 seconds) Based on this output, which statement is correct?

A network engineer runs the following command on Router R1: R1# show ip dhcp server statistics Memory usage 26140 Address conflicts 0 Pool statistics Pool IP addresses Requests Offers Acks Naks Declines Releases POOL1 10-20 50 45 40 5 2 3 Based on this output, which statement is correct?

A network engineer runs the following command on Router R1: R1# show ip dhcp pool POOL1 Pool POOL1 : Utilization mark (high/low) : 100 / 0 Subnet size (first/next) : 0 / 0 Total addresses : 10 Leased addresses : 10 Pending event : none 1 subnet is currently in the pool : Current index IP address range Leased addresses 192.168.1.11 192.168.1.10 - 192.168.1.19 10 Based on this output, which statement is correct?

A network engineer runs the following command on Router R1: R1# show ip dhcp snooping binding MacAddress IpAddress Lease(sec) Type VLAN Interface AA:BB:CC:01:02:03 192.168.1.10 86400 dhcp-snooping 10 GigabitEthernet0/1 AA:BB:CC:01:02:04 192.168.1.11 86400 dhcp-snooping 10 GigabitEthernet0/1 AA:BB:CC:01:02:05 192.168.1.12 86400 dhcp-snooping 10 GigabitEthernet0/2 Based on this output, which statement is correct?

A network engineer runs the following command on Router R1: R1# show ipv6 dhcp interface GigabitEthernet0/1 GigabitEthernet0/1 is in server mode Using pool: POOL6 Preference value: 0 Hint from client: ignored Rapid-Commit: disabled Based on this output, which statement is correct?

A network engineer runs the following command on Router R1: R1# show ip dhcp relay information trusted Interface Trusted GigabitEthernet0/1 Yes GigabitEthernet0/2 No Based on this output, which statement is correct?

A network engineer runs the following command on Router R1: R1# show ip dhcp database URL : flash:/dhcpdb Read/write : Read/Write Last updated : Mar 01 2020 00:00:00 Status : Last read succeeded. Next write scheduled in 0 seconds. Based on this output, which statement is correct?

Examine the following DHCP configuration on router R1: ip dhcp excluded-address 192.168.1.1 192.168.1.10 ! ip dhcp pool POOL1 network 192.168.1.0 255.255.255.0 default-router 192.168.1.1 dns-server 8.8.8.8 lease 0 2 30 ! interface GigabitEthernet0/0 ip address 192.168.1.1 255.255.255.0 ip helper-address 192.168.2.2 no shutdown What is the effect of this configuration?

Consider the following DHCPv6 configuration on router R2: ipv6 dhcp pool DHCP6_POOL dns-server 2001:db8::1 domain-name example.com ! interface GigabitEthernet0/0 ipv6 address 2001:db8:1::1/64 ipv6 dhcp server DHCP6_POOL ipv6 nd other-config-flag no shutdown What is the effect of this configuration?

Router R3 has the following DHCP configuration: ip dhcp pool POOL2 network 10.10.10.0 255.255.255.0 default-router 10.10.10.1 dns-server 10.10.10.2 lease 7 ! interface GigabitEthernet0/0 ip address 10.10.10.1 255.255.255.0 ip dhcp relay information option no shutdown What is the problem with this configuration?

Router R4 has the following DHCPv6 configuration: ipv6 dhcp pool DHCP6_POOL2 address prefix 2001:db8:2::/64 dns-server 2001:db8::1 ! interface GigabitEthernet0/1 ipv6 address 2001:db8:2::1/64 ipv6 dhcp server DHCP6_POOL2 ipv6 nd managed-config-flag no shutdown What is the effect of this configuration?

Router R5 has this DHCP configuration: ip dhcp pool POOL3 network 172.16.0.0 255.255.255.0 default-router 172.16.0.1 option 150 ip 10.10.10.10 ! interface GigabitEthernet0/0 ip address 172.16.0.1 255.255.255.0 no shutdown What is the purpose of the option 150 command?

Router R6 has the following DHCPv6 configuration: ipv6 dhcp pool DHCP6_POOL3 address prefix 2001:db8:3::/64 lifetime 3600 600 dns-server 2001:db8::1 ! interface GigabitEthernet0/2 ipv6 address 2001:db8:3::1/64 ipv6 dhcp server DHCP6_POOL3 ipv6 nd managed-config-flag no shutdown What is the effect of the lifetime parameters 3600 and 600?

What is the default lease duration for a DHCPv4 address pool on a Cisco IOS router?

In DHCPv6, what is the purpose of the 'managed-config-flag' in Router Advertisement messages?

Which DHCP message type is used by a client to renew its lease before it expires?

Which TWO commands can be used to verify DHCP IPv4 server operation and address pool utilization on a Cisco IOS router? (Choose TWO.)

Which TWO statements about DHCP IPv6 (DHCPv6) operation are true? (Choose TWO.)

Which THREE symptoms indicate a DHCP IPv4 starvation attack or address pool exhaustion? (Choose THREE.)

Which TWO configuration steps are required to enable a Cisco IOS router as a stateful DHCPv6 server for clients on interface GigabitEthernet0/0? (Choose TWO.)

Which THREE commands can be used to troubleshoot DHCPv6 client address assignment issues on a Cisco IOS router acting as a DHCPv6 client? (Choose THREE.)

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?

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?

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?

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?

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?

A network engineer runs the following command to troubleshoot DHCPv6 relay on router R1: R1# debug ipv6 dhcp relay Output: IPv6 DHCP relay: Received SOLICIT message from FE80::1 on GigabitEthernet0/0 IPv6 DHCP relay: Forwarding SOLICIT to server 2001:DB8:2::1 via GigabitEthernet0/1 IPv6 DHCP relay: Received ADVERTISE message from server 2001:DB8:2::1 via GigabitEthernet0/1 IPv6 DHCP relay: Forwarding ADVERTISE to client FE80::1 via GigabitEthernet0/0 IPv6 DHCP relay: Received REQUEST message from FE80::1 on GigabitEthernet0/0 IPv6 DHCP relay: Forwarding REQUEST to server 2001:DB8:2::1 via GigabitEthernet0/1 IPv6 DHCP relay: Received REPLY message from server 2001:DB8:2::1 via GigabitEthernet0/1 IPv6 DHCP relay: Forwarding REPLY to client FE80::1 via GigabitEthernet0/0 What does this output indicate?

A network engineer runs the following command to verify DHCPv4 pool configuration on router R1: R1# show ip dhcp pool DHCP_POOL Output: Pool DHCP_POOL : Utilization mark (high/low) : 100 / 0 Subnet size (first/next) : 0 / 0 Total addresses : 254 Leased addresses : 100 Pending event : none 1 subnet is currently in the pool : Current index IP address range Leased addresses 192.168.1.1 192.168.1.1 - 192.168.1.254 100 What does this output indicate?

A network engineer runs the following command to verify DHCPv6 pool configuration on router R1: R1# show ipv6 dhcp pool Output: Pool DHCPv6_POOL : Prefix number: 1 Prefix: 2001:DB8:1::/48 Preferred lifetime 604800, valid lifetime 2592000 Expires at Mar 01 2025 12:00 PM (2592000 seconds) DNS server: 2001:DB8::1 Domain name: example.com Active clients: 5 What does this output indicate?

A network engineer runs the following command to verify DHCPv4 server conflict detection on router R1: R1# show ip dhcp conflict Output: IP address Detection method Detection time VRF 192.168.1.50 Ping Mar 01 2025 10:00 AM default 192.168.1.75 Gratuitous ARP Mar 01 2025 11:00 AM default What does this output indicate?

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

Which DHCPv4 message type does a client send to request a specific IP address previously offered?

What is the default DHCPv6 client DUID type on a Cisco IOS-XE router?

In DHCPv6, what is the purpose of the SOLICIT message?

Which DHCPv4 option is used by a client to request a specific IP address in the DHCPREQUEST message?

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

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

What is the default DHCPv4 renewal time (T1) as a percentage of the lease time?

Which DHCPv6 option carries the DNS recursive name server information?

Drag and drop the steps to configure a DHCP pool and relay agent on a Cisco router into the correct order, from first to last.

Drag and drop the steps to troubleshoot DHCP (IPv4 and IPv6) adjacency or connectivity failures into the correct order, from first to last.

Drag and drop the steps to verify and validate DHCP (IPv4 and IPv6) operational state into the correct order, from first to last.

Which TWO statements about DHCPv6 prefix delegation are true? (Choose TWO.)

Which TWO actions will prevent a Cisco IOS router from acting as a DHCPv4 server for a specific VLAN? (Choose TWO.)

Which TWO statements about DHCPv6 stateless autoconfiguration (SLAAC) are true? (Choose TWO.)

Which TWO statements about DHCPv4 option 82 are true? (Choose TWO.)

Which TWO statements about DHCPv6 rapid commit are true? (Choose TWO.)

An engineer configures DHCPv6 prefix delegation on a Cisco router acting as a requesting client. The router receives a valid IA_PD prefix from the server, but no route for the delegated prefix appears in the routing table. Which is the most likely explanation?

A network engineer configures a DHCP snooping trusted port on a switch to allow a legitimate DHCP server. However, clients connected to untrusted ports on the same VLAN cannot obtain IP addresses. The DHCP server is reachable and the switch shows no DHCP snooping drops. Which is the most likely explanation?

An engineer configures a DHCP server on a Cisco router to assign IP addresses from a pool. Clients receive addresses, but when the engineer checks 'show ip dhcp binding', no bindings are displayed. Which is the most likely explanation?

A router configured as a DHCPv6 relay agent is not forwarding DHCPv6 requests from clients to the server. The relay interface has 'ipv6 dhcp relay destination' configured. Clients are on a different VLAN. Which is the most likely explanation?

An engineer configures DHCPv4 on a router with multiple pools for different subnets. Clients in subnet A receive addresses correctly, but clients in subnet B receive addresses from subnet A's pool. The router has 'ip dhcp relay' configured. Which is the most likely explanation?

A router is configured as a DHCPv6 client on an interface using 'ipv6 address dhcp'. The router receives a valid IPv6 address from the server, but the address is not used for outgoing traffic. Which is the most likely explanation?

An engineer configures DHCP snooping on a switch to prevent rogue DHCP servers. After enabling, legitimate DHCP clients on VLAN 10 cannot obtain addresses. The DHCP server is connected to a trusted port. The switch shows 'show ip dhcp snooping binding' with no entries. Which is the most likely explanation?

A router configured as a DHCPv4 server uses a pool with 'bootfile' and 'next-server' options for PXE boot. Clients receive the DHCP offer with the correct bootfile, but they fail to download it. Which is the most likely explanation?

An engineer configures DHCPv6 prefix delegation on a router with multiple requesting interfaces. The router receives a /48 prefix from the server, but only one interface gets a /64 sub-prefix. Which is the most likely explanation?