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28 Cards in this Set
- Front
- Back
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What are some common differences when you configure a router vs a Layer 2 switch? |
- All router interfaces are down by default - Routing protocols do not exist at Layer 2 - VLANS do not exist on routers |
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What is the difference between ISR and Aggregate Routers? |
ISR - many services in one device, can add security features Aggregate - first generation routing |
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List some different Cisco Router models |
ISR generation 1 - 1800, 2800, 3800 ISR generation 2 - 1900, 2900, 3900 Aggregation - 1000, 9000 |
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Name some routing protocols used |
OSPF EIGRP RIP ISIS BGP |
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What is the Address Resolution Protocol (ARP) used for? |
Matching network layer MAC addresses to link layer IP addresses. |
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Explain how you would find where a PC is located on a network using ARP |
- Ping an IP address to generate an ARP request/reply - check the MAC address table to determine on which port the device lies |
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What is HSRP (Hot Standby Router Protocol)? |
- Cisco proprietary - Provides a virtual MAC address and an IP address that is shared among a group of configured routers - Lower devices don't know if a link is down because their default gateway is a virtual IP address that fails over between devices |
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What is a key difference between HSRP and GLBP? |
GLBP allows for load-balancing |
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What is enhanced object tracking and what is it used for? |
Allows HSRP to monitor a link and change its priority value if a link that is being tracked were to fail - seamless fail over - used when you have more than one downstream link |
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What are MTUs and why are they important? |
- the largest size a data packet can be to traverse the wire - packet will be dropped if it is too large - If the packet is too big, it must be fragmented |
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What is a limitation of a static route? |
No dynamic failover |
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What situations call for the use of static routing? |
- very small, non-redundant environments - default routes through Firewalls
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Describe two types of routing protocols |
- Distance vector: only knows the next hop; takes longer to reconverge - link-state: knows everything about topology; maintains 3 tables |
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What is a floating static route used for? |
"Poor man's redundancy" If a route fails, the static with a higher administrative distance takes over |
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Why use loopback interfaces? |
- Virtual interfaces, so they never go down - Good for testing and stability |
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Why are K values important to remember in EIGRP? |
They are values that can be changed to influence which routes are preferred - if K values are mismatched, then EIGRP will not form neighbors |
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What K values should you change? |
K1 and K3 = bandwidth and delay |
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What is the basic command syntax required to get EIGRP running? |
router eigrp [AS-number] network [IP-address] [subnet-mask] |
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What is a feasible successor and why is it important? |
All backup routes without loops that are stored in the topology table Inserted into the routing table if the successor goes down |
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What does it mean to be "stuck in active"? |
- Successor route is down and there is no FS in the topology table - Actively querying neighbors to find a route |
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How would you troubleshoot an EIGRP peer not coming up? |
debug ip eigrp packets show ip interface brief show running-config Ping/traceroute
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What is included in LSA #3? |
summary routes from area border router |
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What is an Area Border Router (ABR) and why is it important? |
ABRs have networks that are in multiple OSPF areas and can do route summarization They can help isolate network issues and keep routing databases smaller |
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Why is route summarization important? |
Controls the size of the routing table and reduces network traffic related to OSPF |
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Why choose OSPF over EIGRP? |
Mixed vendor environment In an environment where proprietary solutions are forbidden More control of metrics to tweak |
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Why would you use Policy Based Routing? |
If you need to route by the source address |
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What are the risks of PBR? |
You might introduce black holes due to next hops disappearing |
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How would you verify PBR? |
show route map traceroute ping show ip route |
