QID:AR137 Question does not match explanation

[greaterzen1]

Hi,

So, QID:AR137 is confusing to me. At least the answer explanation compared to the question.

The question states the following: Which feature drops packets if the source address is not found in the snooping table?

• Binding table recovery
  
• IPv6 Destination Guard
  
• IPv6 Prefix Guard
  
• IPv6 Source Guard
  

Explanation:

IPV6 source guard filters in bound traffic on L2 switch ports that are not in the ipv6 binding table. The binding table stores the following information:

• ipv6 address 
  
• mac address
  
• VLAN
  
• interface ID
  

Help me understand, where is the "snooping table? Nonetheless, I did some research. The following below is a statement from cisco white pages "IPv6 First-Hop Security Configuration Guide, Cisco IOS XE Release 3S" 

Reference Link: https://www.cisco.com/c/en/us/td/docs/io...guard.html


"  IPv6 Source Guard blocks any data traffic from an unknown source. For example, one that is not already populated in the binding table or previously learned through Neighbor Discovery (ND) or Dynamic Host Configuration Protocol (DHCP) gleaning."

I don't doubt there is a "snooping table" somewhere in the world of network engineer. However, per the documentation source guard and ipv6 prefix guard are snooping features not related to a snooping table. Now, I'd say leave it,  if the intent is to use cisco trickery to make the test question as close to the exam as possible. Cisco tends to use misdirection and or use weird wording to trick candidates, which in my opinion is dishonest. However, if this is an honest typo, please fix.

Thanks, and my apologies for the long winded explanation. 

[help_desk]

We have removed the question as it was outdated and inappropriate.