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Miscellaneous Questions

March 23rd, 2017 in ICND2 200-105 Go to comments

Question 1

Explanation

Switch stacking technology allows the network engineer to make that stack of physical switches act like one switch. The stacking cables together make a ring between the switches. That is, the switches connect in series, with the last switch connecting again to the first.

switch_stacking.jpg

Answer B is not correct as switch stacking is about connecting switches together so that they act as one switch, not about adding and removing hosts.

Answer C is not correct because switch stacking has nothing to do with performance of high-needs applications.

Surely switch stacking provides redundancy as stacking creates a ring of connection with two opposite paths. Whenever a frame is ready for transmission onto the path, a calculation is made to see which path has the most available bandwidth. The entire frame is then copied onto this half of the path.

With switch stacking, STP, CDP and VTP would run on one switch, not multiple switches. Also there would be one MAC address table, and it would reference all ports on all physical switches so we may say switch stacking has better resource usage. Also if we consider all stacking switches as one logical switch then surely the port density is increase very much. Therefore answer D is the most suitable one.

Reference: http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-3750-series-switches/prod_white_paper09186a00801b096a.html

Question 2

Question 3

Explanation

The Domain Name System (DNS) is used to resolve human-readable domain names like www.microsoft.com into machine-readable IP addresses like 104.43.195.251. DNS also provides other information about domain names, such as mail services.

Suppose Microsoft has some data centers located at different locations. For example one in USA and one in Canada. With normal DNS, only the data center in USA is chosen as the “active” server and the DNS server will return the IP address of the data center in USA when being asked.

With the use of intelligent DNS, the DNS server may return the IP addresses of the data center in USA or in Canada, depends on some rules (user’s geographical location, data center’s available resources…). Thus intelligent DNS helps share the load among the data centers -> Answer B is correct.

The Global Site Selector (GSS) is a crucial component of any data center architecture that requires a secure site-to-site global load balancing. The GSS allows businesses to deploy global Internet and intranet applications with the confidence that all application users will be quickly rerouted to a standby data center during a primary data center outage or overload.

Therefore GSS works in the same way as intelligent DNS but we are not sure about the answer “it eliminates the need for a GSS”. Maybe GSS can cooperate with intelligent DNS for better performance.

Note: The traffic flow itself (between the client and the server) never traverses the GSS or intelligent DNS. The GSS/DNS simply tells the client which server to target by resolving a name to an IP address.

Question 4

Explanation

Switched Port Analyzer (SPAN) is used to analyze network traffic passing through ports on a switch. For example we can configure the Switch to monitor its interface Fa0/0, which connects to the Core, by sending all traffic to/from Fa0/0 to its Fa0/1 interface. At Fa0/1 interface we connect to a computer and use such a software like Wireshark to capture the packets.

port_mirror.jpg

Question 5

Explanation

The following diagram illustrates the key difference between traffic policing and traffic shaping. Traffic policing propagates bursts. When the traffic rate reaches the configured maximum rate (or committed information rate), excess traffic is dropped (or remarked). The result is an output rate that appears as a saw-tooth with crests and troughs. In contrast to policing, traffic shaping retains excess packets in a queue and then schedules the excess for later transmission over increments of time. The result of traffic shaping is a smoothed packet output rate.

traffic_policing_vs_shaping.jpg

Note: Committed information rate (CIR): The minimum guaranteed data transfer rate agreed to by the routing device.

Question 6

Question 7

Question 8

Comments (1) Comments
  1. Kumo
    April 24th, 2017