Sunday, August 17, 2008

Thanks for stopping by! :)

It's Sunday, August 17, and here are the answers to yesterday's Cisco training questions!

CCNA Certification And CCENT Certification:

In the world of wireless networking, what's the difference between a Basic Service Set and an Extended Service Set? (The answer "One is extended and the other is not" isn't quite what I'm looking for! ;) )

Answer: A BSS has only one Access Point (AP); an ESS has more than one.

CCNA Security Certification / CCNP ISCW Exam:

What is "3704 filtering", and what does it have to do with network security?

Answer: RFC 3704 (an updated version of RFC 2827) recommends that packets from the following network ranges be prohibited from entering your network: /8 /8 (RFC 1918 Class A private range) /8 (loopback address range) /12 (RFC 1918 Class B private range) /16 (RFC 1918 Class C private range) /4 (reserved for IP multicasts) /4 (RFC 1918 Class E private range)

Blocking these address ranges for incoming traffic on your network's perimeter routers is sometimes called "2827 filtering" or "3704 filtering", referring to the original and updated RFCs that discuss this topic in a great deal of detail.

CCNP Certification / BSCI Exam:

What is an EIGRP Stub Router, and why would you configure such a router?

Answer: While EIGRP does not have the stub area options that OSPF does, EIGRP does allow a router to be configured as stub. This is commonly done with a hub-and-spoke configuration where the spoke routers do not have the resources or the need to keep a full routing table.

Since the spoke's next hop will always be the hub, all the spoke really needs is a default route. For this reason, the only neighbor an EIGRP stub router can have is the hub router. (Obviously, the hub would never be configured as stub.)

Configuring EIGRP stub routers also combats the SIA problem. EIGRP stub routers are not queried for routes when the hub does not have a feasible successor for a successor route that has gone down. This limits the scope of EIGRP Query packets and is a popular reason for configuring EIGRP stub routing.

CCNP Certification / BCMSN Exam:

What command resulted in the following output?

R3# ?
Ethernet0 - Group 1
Local state is Active, priority 100, may preempt
Hellotime 3 sec, holdtime 10 sec
Next hello sent in 0.706
Virtual IP address is configured
Active router is local
Standby router is expires in 8.816
Virtual mac address is 0000.0c07.ac01
2 state changes, last state change 00:02:34

Answer: That's HSRP information, and the command is show standby.

CCNP / ONT Exam: (My ONT Study Package will be out tomorrow, Monday, August 18!)

What protocol is used by the WCS to communicate with Wireless LAN Controllers?

Answer: SNMP.

There's a new CCNA Security exam on the main site , with quite a few new practice exams and tutorials on the way! Check it out!

To your success,

Chris Bryant
CCIE #12933

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