Interview questions I could not answer properly

I just had a 2 hour interview in networking. I am a CCNA but the things they asked me were basic.

1. What are the advantages of BUS TOPOLOGY, RING TOPOLOGY and STAR Topology.
I only know about start topology so I could not answer about other topologies.

2. what is the difference between Duplex and Speed? and When will the switch get a duplex mix match? I could not answer that. How to fix a duplex mix match situation.

3. What is a broadcast storm?
SR ZakNetwork Solutions Asked:
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I don't blame you as I had to look it up myself.

Here is the answer to the difference between the Network Topologies:

Duplex is bidirectional communication where speed is the bitrate.

"On an Ethernet connection, a duplex mismatch is a condition where two connected devices operate in different duplex modes, that is, one operates in half duplex while the other one operates in full duplex."

You fix the problem by simply changing the appliance to one that's more compatible and support duplexing or maybe there's a switch to toggle between simplex and duplex communication.

A broadcast storm is when a device hog the network resources (overwhelmed the network by continuously producing multicast or broadcast traffic) so as to render the network unsable to transport normal traffic.

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1. Bus Topology is more of a reference back to the copper wire back bone days.  Bus Topology basically means multiple computers accessing a single copper line (back bone).  This is where CSMA/CD plays a big role.  Bus Topology held an advantage at the time of having a line available all the time for transmitting and receiving (Unless there is a collision).  
Ring topology is exactly as it sounds.  The design was based on a carrier token that would pass from one computer to the next and eventually come back around to the first computer.  This design was better then the Bus topology in the fact that collisions were virtually eliminated since a computer could only communicate if it had the token.  In a single ring topology transmission could only happen in one direction.  This spawned the dual ring design which would allow an end station to pass a toke in the other direction.
Star Topology is the basic design of most networks (my opinion).  This design is based around a central location communicating out to the end stations.  This central location is a switch or router.  The star topology holds the advantage of isolating collision domains and providing instant access to the network.  
2.  Duplex refers to how communications are handled meaning is the communication either half duplex or full duplex.  Half duplex means the port is either transmitting or receiving.  Full duplex means the port is transmitting and receiving at the same time.  Speed is the rate communications are happening i.e. 10 Mbs, 100 Mbs, 1000 Mbs.  You would see duplex mismatches when a device is configured different then the port.  Example, a switch port is configured  for full duplex and the device is configured for half duplex.  The port and the device have to match, typically setting the port and the device to auto negotiate will resolve this issue
3.  Broadcast storms are when devices on the network send out packets to the entire network.  Sometimes switches will do this when they are trying to resolve which end stations are located on which ports.  This can also happen if an end station tries to communicate out to every device on the network continuously.
Bryant SchaperCommented:
To add to Justins comments as well.

1. Collisions domains are reduced with switches, so no hubs, although you would be hard pressed to buy one now I bet.  You really see Bus deployments, I have seen ring in carrier fiber networks.

2.  Auto negotiate is the standard setting but some devices do not do this well, so to resolve the problem you can set duplex to half or full on both ends.

3.  Viruses and malware as well are known culprits.  These could like a network, and n many network switches you can monitor and shutdown a port if violates a condition.  Certainly with Cisco, but I am sure Juniper, HP and other managed switches will have it too.
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Bill BachPresident and Btrieve GuruCommented:
Someone asked the first question in this century?  I doubt that anyone uses bus networking any more -- this was thick Ethernet (Thicknet) and thin RG-58 coaxial Ethernet (Thinnet).  Token Ring was one of the early ring technologies, but this has been dead for years and years now.  (OK, so an old guy like me might have an old TR adapter lying around, but I haven't needed it since 1997.)  ARCnet was a 2.5Mbps ring network topology that were implemented in a "star" design, using concentrators, which worked over RG-62 coax, CAT3 TP, and even barbed wire!  It was replaced by TCNS, which was 100Mbps, and would work over the same cabling as well as fibre optic cabling.  All of these technologies are long since gone from the planet, though -- unless you find a REALLY old environment somewhere.
Lol, I thought the same.  We're not exactly trying to network Commodores or Radio Shack PCs but I guess they want you to remember how it all started.
Bryant SchaperCommented:
Yes, totally agree. Would honestly say the first two questions are a bit outdated.  Even with speed and duplex.  Makes me wonder what network they had where these questions would be relevant.
Bill BachPresident and Btrieve GuruCommented:
My first network was Corvus Omninet (also a bus topology) on the Apple ][+ computers which used vampire taps (look THAT up in your Funk & Wagnalls), and I remember upgrading to AT&T StarLAN in 1988, running silver satin cable (8-wire, non-twisted) at a whopping 1Mbps.  Whee!  

Sadly, I do still see companies today running 100Mbps connections with auto-sense, where they get duplex mismatches from time to time, so I do understand the impetus behind this question.
Bryant SchaperCommented:
I guess, I once took over as SM at a company with an old AS/400 and thinknet.  What a pain, resoldering connectors.

I can see the point of the question, but find it funny they would want a CCNA to manage it.  Maybe it is consulting firm.
Don JohnstonInstructorCommented:
Was this an initial interview? Maybe with HR?  Because I can't see a technical manager asking the first question today. It almost seems like they were provided to someone non-technical to ask.  These questions feel like they came right out of the module review questions for ICND1 and ICND 2 courseware.

No offense intended, but if I was conducting the interview of a current CCNA and they couldn't answer these questions, I would be questioning whether they really had CCNA certification.  The first two questions have been in the CCNA question pool literally since the very first CCNA exam.
SR ZakNetwork Solutions Author Commented:
I did not expect these basic questions to cause a buzz in my mind. I guess I never took these topics serious enough. I am now going to read CCNA again specially the 1st 3 chapters to clear the topology designs and pros and cons. The company manufactures switches - just layer 2 not the high end layer3 or blade switches. I see a connection to these questions.

Thank you all
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