A trunk link must be configured between the two switches. Trunk links carry multiple VLAN information. Fast Ethernet 1/0 must be configured as a trunk to allow communication between hosts of the same VLAN through the switches. The command “show vlan brief” displays only access links, after the port Fa1/0 is configured as an access link, the switches will not be able to transmit any VLAN information with each other. - - - - - - - - - - - - - - -(zz-update-20151221) - - - //modified this question, because when I got here there were 2 correct answers - - - - //Came back and modified again after testing this config on PacketTracer - - - - NOTE: working Trunk links are necessary to pass data from hosts that aren't in the native vlan, which is why they won't be able to communicate from the SW2 side to the SW3 side if the connecting link becomes an Access-Link, rather than a Trunk Link. - - - - NOTE: the "native" VLAN is set on the Trunk-Link-Interface on each switch with the command: "switchport trunk native vlan [1-?]" - - - - - Regarding the "default-vlan-1" choice, it is not possible to say what will 'always' happen without seeing the other configs // Remember the word: 'Default" is merely a default system 'label' that can be changed, it doesn't tell you what the "native" vlan is, because that is a Trunk-Link issue and you have to use the command "show-interface-trunk" command to see what the native-vlan is "ON THAT LINK" //EXAM Tip: on the choice about the default-vlan-1; as mentioned earlier, right-out-of-the-box, and in most cases: vlan-1 will be the native-vlan, and hosts on that vlan will be able to communicate with each other with, OR WITHOUT any trunk links, but what make this a less-correct answer than the one regarding non-native-vlans is the two words "All" and 'always', = = any imaginable situation which would make this false, leads to this being a bad choice if there is a better one, that will 'always be true' - - - - [Good-Luck !]