Selected Answer: B Notice the source MAC address is an HSRP MAC: 0000.0c07.acxx

Selected Answer: B It's only a warning. The groups are different, so no problem

Selected Answer: B look at the MAC address in the LOG Message: "%IP-4-DUPADDR: Duplicate address 10.10.1.1 on FastEthernet1/0, sourced by 0000.0c07.ac28" ... The MAC Address is a Virtual HSRP MAC Address!!!

Selected Answer: B I've tested it again and caught this bug, same error actually. Anyway, you can cache MAC manually, by default yes, it belongs to the HSRP process, the difference is only in the groups 10 vs 11; *Jan 10 10:11:31.992: %IP-4-DUPADDR: Duplicate address 10.99.0.254 on Ethernet0/1.10, sourced by 0000.0c07.ac0a cisco_R5# cisco_R5#s runn int ethernet 0/1.10 Building configuration... Current configuration : 119 bytes ! interface Ethernet0/1.10 encapsulation dot1Q 10 ip address 10.99.0.5 255.255.255.0 standby 11 ip 10.99.0.254 <<<<<<<<<<<<<< end cisco_R5#

Actually no, there will be problems. You can't have duplicate active IPs tied to different MACs on a subnet. The reason HSRP works is that only one host (router) in an HSRP group is active with the VIP/MAC. But with two separate groups, both are talking and in this case, the IPs conflict

Selected Answer: C cisco_R3(config-subif)# *Dec 22 20:44:43.970: %IP-4-DUPADDR: Duplicate address 10.111.12.6 on Ethernet0/0.70, sourced by aabb.cc00.5000 cisco_R3(config-subif)#do show runn int Ethernet0/0.70 Building configuration... Current configuration : 123 bytes ! interface Ethernet0/0.70 encapsulation dot1Q 70 ip address 10.111.12.1 255.255.255.248 standby 11 ip 10.111.12.6 end cisco_R3(config-subif)# *Dec 22 20:45:13.974: %IP-4-DUPADDR: Duplicate address 10.111.12.6 on Ethernet0/0.70, sourced by aabb.cc00.5000 cisco_R3(config-subif)#

remote end: cisco_R5(config-subif)#do s runn interface ethernet 0/0.70 Building configuration... Current configuration : 96 bytes ! interface Ethernet0/0.70 encapsulation dot1Q 70 ip address 10.111.12.6 255.255.255.248 end cisco_R5(config-subif)#

other end: *Jan 10 10:11:01.888: %IP-4-DUPADDR: Duplicate address 10.99.0.254 on Ethernet0/1.10, sourced by 0000.0c07.ac0b cisco_R2(config-subif)# cisco_R2(config-subif)#do s runn int ethernet 0/1.10 Building configuration... Current configuration : 119 bytes ! interface Ethernet0/1.10 encapsulation dot1Q 10 ip address 10.99.0.2 255.255.255.0 standby 10 ip 10.99.0.254 <<<<<<<<<<<<<<<<<<<<<<< end cisco_R2(config-subif)# *Jan 10 10:11:31.993: %IP-4-DUPADDR: Duplicate address 10.99.0.254 on Ethernet0/1.10, sourced by 0000.0c07.ac0b cisco_R2(config-subif)#

fix it: cisco_R2(config-subif)#int ethernet 0/1.10 cisco_R2(config-subif)#no standby 10 <<<<<<<<<<<<<<<<<<< *Jan 10 10:16:33.457: %HSRP-5-STATECHANGE: Ethernet0/1.10 Grp 10 state Active -> Disabled cisco_R2(config-subif)# standby 11 ip 10.99.0.254 <<<<<<<<<<<<<<<<<<< cisco_R2(config-subif)# *Jan 10 10:17:03.504: %HSRP-5-STATECHANGE: Ethernet0/1.10 Grp 11 state Speak -> Standby cisco_R2(config-subif)#do s standby br P indicates configured to preempt. | Interface Grp Pri P State Active Standby Virtual IP Et0/0.10 200 100 Active local unknown 192.168.255.254 Et0/1.10 11 100 Standby 10.99.0.5 local 10.99.0.254 <<<<<<<<<<<<<<< cisco_R2(config-subif)# cisco_R2(config-subif)#do s runn int ethernet 0/1.10 ! interface Ethernet0/1.10 encapsulation dot1Q 10 ip address 10.99.0.2 255.255.255.0 standby 11 ip 10.99.0.254 end

you are wrong... look at the MAC address in the LOG Message: "%IP-4-DUPADDR: Duplicate address 10.10.1.1 on FastEthernet1/0, sourced by 0000.0c07.ac28" ... The MAC Address is a Virtual HSRP MAC Address!!!

Selected Answer: B The sourced MAC address is an HSRP MAC: 0000.0c07.acxx (xx is the HSRP group number in hexadecimal format). Both HSRP groups (groups 50 & 28) use the same virtual IP address, which is causing the issue.