Chap 15 - IP Services Flashcards
Name 5 reasons why synchronizing time between devices is important.
- Managing password time change intervals
- Encryption key changes
- Checking certification validation and expiration
- Correlation of security-based events across multiple devices
- Troubleshooting correlating events to identify root cause
What stratum is an NTP client that is attached directly to an authoritative time source?
Stratum 1
What is the highest stratum level there is?
Stratum 15
If a router is configured as NTP Master stratum 1 what will the show cmd say under ‘ref clock’
.LOCL.
If a router configured as an NTP client points to 2 NTP servers which one will it sync to?
The NTP server with the highest stratum.
2 things that describe the most common way organizations design their NTP environment?
- 2 Devices point to 2 different external NTP servers
- Configure the 2 devices to point to each other as NTP peers
What do NTP peers do?
They act as clients and servers to each other, in the sense that they try to blend their time to each other.
What is the NTP peer model for?
For designs where other devices can act as backup devices for each other and use different primary reference sources.
How long does it take NTP peers to synchronize?
Maximum rate of 2 minutes per query.
What are 3 FHRPs?
- Hot Standby Routing Protocol (HSRP)
- Virtual Router Redundancy Protocol (VRRP)
- Gateway Load Balancing Protocol (GLBP)
What is object tracking used for?
It is used so that other devices can act as backup devices for each other and use different primary reference sources.
What is object tracking usually used for?
For tracking the availability of the WAN interface or the existence of a route learned via that next hop.
Upon bootup how does HSRP determine which router will be active and how does it deal with a tie?
- Router with the highest priority wins
- In the event of a tie the highest IP address wins
What is the default priority in HSRP?
100
In a case where there are 3 HSRP routers and the active router fails which router takes over?
The router with the second highest priority.
In HSRPv2 what are the 2 valid poll intervals?
- 1 to 254 seconds
- 15 to 999 msec
Name 2 facts that describe how load balancing is done in HSRP?
- Configure multiple instances on the same interface
- Change the priorities
Name 6 items that can be viewed when using the command ‘show standby brief’?
- local interface’s priority
- whether preemption is enabled
- current state
- active speaker’s address
- standby speaker’s address
- VIP gateway instance for that standby group.
Name 4 items that can be viewed using the command ‘show standby’?
- Group name
- Timers
- Time since the last state change
- Number of state changes for the HSRP instance
In VRRP what is the active router called?
Master Router
In VRRP what are the non-active routers called?
Backup Routers
What is the difference between how HSRP implements preemption vs how VRRP does it?
- HSRP - preemption must be configured
- VRRP - preemption is on by default
Is VRRPv3 backward compatible with VRRPv2?
No
What is the valid priority range for VRRPv3?
0 to 255