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Troubleshooting VLANs

Unanswered Question
Jan 7th, 2016
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I'm studying VLANs and I have a doubt.

I'm in the following scenario:

I have three PC: PCA, PCB, PCC and each of them belong at differents VLANs and they are connected to a switch on three separated FastEthernet ports. The switch is connected to a router which is useful to connect PC1, PC2, PC3 (router on a stick). PCB can ping PCA and PCC, but can't telnet to the switch.

The correct answer of this multiple choice is: The switch needs an appropriate default gateway assigned.

My question is: If PCB can ping PCA and PCC why PCB can't telnet the switch? I think that if ping success it mean that ping leaves PCB, goes to he router and than go to PCA or PCC

I don't understand why PCB is not able to telnet to the switch from host B while ping can reach the others two hosts  successful

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Mark Malone Thu, 01/07/2016 - 05:30
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If your on the same subnet it would work but the answer is correct if the switch has no default-gateway set how does it know to send traffic back to you on a different subnet

when everything is on the same subnet no need for gateway as it will arp the request anyway and be reachable but layer 2 devices without any gateway set will not get traffic out of its local broadcast domain

Pinging the switch is just the MGMT interface as its layer 2 it has nothing to do with the default-gateway and how traffic is sent back out , all switches at layer 2 would all have an ip in the same range for mgmt. purposes and reachability to make sure switch is up but that's al the ip is used for on layer 2 switch


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