How do you enable HSRP on a router?
Enter interface config mode:
(config-if)# standby 1 192.168.1.1
The “1” is the HSRP group that this interface belongs to and the 192.168.1.1 is the virtual IP that will be shared.
How would you find the MAC address of a HSRP virtual IP?
show ip arp
What are the first 10 characters of a HSRP version 1 virtual MAC address?
0000.0c07.ac
NOTE: the full MAC is 0000.0c07.ac01
The “01” at the end is the HSRP group number configured on the router’s interface standby command.
What is the default HSRP priority value?
100
It can be any value between 0 and 255
How do you manually assign a HSRP value to force election of an active router in a HSRP pair?
One way is to assign a higher priority than 100 on the router we want to be the active member of the pair.
(config-if)# standby 1 priority 110
What does the “preempt” command do on an interface configured for HSRP?
Preempt allows a router that comes online with a higher HSRP priority to overthrow the current active router and become the new active router. The old one would go into a standby state.
What happens if two routers come online at the exact same time with the same HSRP priority?
The router with the higher physical IP on the subnet wins.
What are the differences of HSRPv1 and HSRPv2
- HSRP 2 supports IPv6
- Group numbers from 0-4095 (not just 0 - 255)
- Virtual MAC changes from 0000.0C07.ACXX to 0000.0C9FXXX
- Multicast changes from 224.0.0.2 to 224.0.0.102
- Different packet formats (HELLO messages, etc)
How do you turn on HSRP version 2?
(config-if)# standby 1 version 2
What is the minimum IOS code that will support HSRPv2?
12.2(46)SE and later
What was the rationale of providing group numbers ranging from 0-4095 in HSRPv2?
More digits allows the HSRP group number / instance to match VLAN IDs.
What are the 5 transition states of HSRP?
- Initial: The state at the start. Also, it is the state after a configuration change or when an interface first comes up.
- Listen: The router knows the virtual IP address. It listens for hello messages from other routers.
- Speak: The router sends periodic hello messages and actively participates in the election of the active or standby router.
- Standby: The router is a candidate to become the next active router and sends periodic hello messages.
- Active: The router currently forwards packets that are sent to the group virtual MAC address. The router sends periodic hello messages.
