I’m posting a new exam-like question today, this time focusing on the layer 2 forwarding logic on LAN switches. This one’s appropriate for the ICND1 exam. Next week, I’ll show a similar question, but with some ICND2-approprate complexity thrown in. The main idea is to predict where the switches in this figure would forward particular frames, at least in their current state.
For those of you who want to time yourselves, just to get a sense for how you’re doing versus the 1:10 or so time goal per question, on average, start your timer when you start reading the question. (If you didn’t see those posts from a few weeks ago, read the post for the main thoughts on how I got the 1:10 per question time.) Next post, I’ll give an answer, as some caveats.
Here’s the question:
Question: SW1 receives a frame on interface Fa0/1, with destination MAC address 0200.4444.4444. The show command output listed below was gathered immediately after this frame was forwarded by the switches. All interfaces on both switches are access interfaces assigned to VLAN 1, and all interfaces are in a working state. Choose the total number of switch interfaces out which this frame is forwarded, on both switches combined.
A) 0
B) 1
C) 2
D) 3
E) 4
F) 6
! SW1 first
SW1#show mac address-table dynamic
Mac Address Table
-------------------------------------------
Vlan Mac Address Type Ports
---- ----------- -------- -----
1 0200.1111.1111 DYNAMIC Fa0/1
1 0200.3333.3333 DYNAMIC Fa0/8
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! SW2 next
SW2#show mac address-table dynamic
Mac Address Table
-------------------------------------------
Vlan Mac Address Type Ports
---- ----------- -------- -----
1 0200.4444.4444 DYNAMIC Fa0/1
1 0200.3333.3333 DYNAMIC Fa0/3Once you pick an answer, feel free to stop your timer. However, I’ll probably focus on the concepts more than the time.
