Question

2.7 and 2.8

2.7 Where would you find the DNS system on your network? What role does it play? Suppose, a user station makes a request to the DNS system. Indicate the likely set of activities that might follow 2.8. "Bandwidth" is an important property of a network. Given two distinct points A and B within a network, a network administrator wants to measure the available bandwidth between these two points as accurately as possible. How would you proceed?

this class is operating systems and networking and this is all I was given was a list of questions to do and am having a hard time with these two

Answer 1

Answer 2.7 :

A DNS (Domain Name System) is a server (local) which maintains a  database for the  name-servers and also handles the requests from the network clients.

Role of DNS :

1) DNS handles requests for IP addresses from all the clients.

2) DNS server has address of various name servers through which it can fetch the necessary IP address and returns the result to the client on the network.

For communication to occur between two devices over a network, both must know each others IP address. But it's not possible to remember IP addresses of all the device, we want to communicate with.  Hence, we make use of the web links or URLs.

If a user station makes request to the DNS system, the following activities will take place :

1) DNS systems considers the URLs or web link provided by the client as a DNS request.

2) DNS system provides the client with the corresponding IP address of the URL or web link by accessing  its central name server database which stores IP addresses information.

3) Communication is now possible between them.

Answer 2.8 :

Bandwidth refers  to the rate at which the data transfer takes place on the path between two points within a network for a specific time.

It can be expressed as maximum bit-rate.

It can be measured in bits per second (bps).

If we are given two points (A and B) within a network, then in order to measure the bandwidth between these two points :

- calculate the throughput when one point acts as the receiver, while other point acts as the sender and determine the number of bytes transmitted in both the sides.

- also determine  the time taken by each of the packet to travel one-way.

Bandwidth for analog signals can be  defined as a difference between the range of frequencies within a band. It is measured in Hertz (Hz).

It is given by,  

B = f2 - f1

Where B = Bandwidth

f2 = upper cutoff frequency

f1 = lower cutoff frequency