LAB 6

Lab 6 : TCP/IP Utilities

1.  Why do we need to ping?

-  Ping is used diagnostically to ensure that a host computer the user is trying to reach is actually operating.

-Ping can be used for troubleshooting to test connectivity and determine response time.

2. Explain the term Sent, Received, Lost dan TTL.

Figure 1

Sent- Total number of the packets sent for the ping process

Received- Total number of the packets received for the ping process

Lost- show if there is any connection problem. If there were any packets lost, there is likely a connection problem.

TTL- Time-to-live (TTL) is a value in an Internet Protocol (IP) packet that tells a network router whether or not the packet has been in the network too long and should be discarded.

3.  Explain what is happening in Figure 1.
      - 

“Ping 117.194.0.24“à Ping only knows how to communicate with IP addresses.

“Reply from 117.194.0.24”à This tells you that the remote server at that IP address replied. What that means, though, is that the entire route across the internet, from your machine through routers and switches and networking equipment and whatever else, worked, as did the return path carrying the server’s reply. If this fails, (“timed out”) then something along the connection between you and the server might be broken, the server might be offline, or the server might not even exist. It’s also possible the server is explicitly configured not to respond to ping requests.

“time<1ms”à This is the round trip time: the time between sending “Are you there?” and receiving “Yes I am!”. In this case, it took < 1 milliseconds. Since the ping is repeated several times, you can see that this time is fairly consistent, which is good. The time varies depending on many factors, including how close you are to the remote server, how many routers and other networking equipment are between you and that server, and more.

“Sent = 4, Received = 4” àOne of the things TCP/IP is designed to deal with is packets  loss. Ideally, every packet you send should get to where it’s going, but for various reasons, that doesn’t always happen. As long as the packets can get there after a retry or two, in normal usage you’d never notice. Ping sends multiple packets and reports specifically on the success rate, so you can see if a particular connection is prone to packet loss.

“Approximate round trip times”à While on average the same kind of packet sent to the same destination should take roughly the same amount of time, that’s also not always the case. Some packets take longer than others, for reasons as diverse as the equipment involved and paths followed. Ping reports these statistics so you can see if a particular connection is prone to this type of problem.

Figure 2

 4.   127.0.0.1 refers to  localhost.

5.        Why do we need to ping 127.0.0.1?                                                                                                   
     - to test whether new network card works with correct driver installed, you can test to ping 127.0.0.1 in command prompt (you can test this even your computer is not connected to network). 

   6.  Explain what is happening in Figure 2 ? 
          - The test is working although it’s not connected to network.iit is because this IP address is also called loopback IP address or localhost, this IP address represents your computer's IP address itself from your computer’s viewpoint.

7. What does it mean by Request timed out?
-    - If a request times out, it means that your computer did not receive a response at all. It's the equivalent of calling someone and having the phone ring hundreds of times until you decide to give up.

8.    Explain what is happening in Figure 3 ?
         -   Message ‘request time out’ out.this is because there is no reply from the destination host. There are many reasons like network connectivity issues, blocking by Firewall etc.

Figure 3.

9.    What is the different between Figure 3 and Figure 4 ?

The first “hops” are the same as the traffic reaches your ISP, while the later hops are different as the packets go elsewhere. For example, below you can see the packets travelling to www.google.com.
   
 

Figure 4.

10.   What is tracert ?
         - Traceroute is a utility that records the route (the specific gateway computers at each hop) through the Internet between your computer and a specified destination computer. It also calculates and displays the amount of time each hop took.

11.   Explain what is happening in Figure 5 ?

Figure 5.

                                                                                                

In Figure 5, the command nslookup was performed that is to find name server information about internet servers by querying Domain Name System(DNS). This command identifies which DNS server the computer is currently configured to use for its DNS lookups. But based on  the Figure 5, the command cannot identify the DNS server maybe due to troubleshooting problems or the computer is not connected to the internet. This test will try to find the host for google page and go4expert page and reach it server. However based on this test, the server for the host cannot be reach.

When  it tried the nslookup command for domain name www.google.com . And we can see the server is still unknown. This time, it gets the non-authoritative answer which refers to DNS records kept on third-party DNS servers, which they obtained from the "authoritative" servers that provide the original source of the data.

Lastly, it tried nslookup on domain name www.go4expert.com. Based on the figure above, we can see that the server is still unknown and it also gets non-authoritative answer.

12.   Explain Physical Address and IP Address.

-         - A physical address also knows as MAC address and  is a binary number in the form of logical high and low states on an address busthat corresponds to a particular cell of primary storage(also called main memory), or to a particular register in a memory-mapped I/O(input/output) device while IP address  is logical numeric address that is assigned to every single computer, printer, switch, router or any other device that is part of a TCP/IP-based network.

  13.   What are differences between Physical Address and IP address.

-  The difference between physical address and IP address are the IP address is an address bound to the network device, i.e., computer, via software. In a Windows-powered computer, the Windows operating system allows the user to configure the IP address the specific workstation will have. This IP address is used to allow all network aware programs, i.e., Internet Explorer, Netscape, Outlook, etc. to use this address when communicating with other hosts. The seventh layer in the OSI model has the IP addresses while for the Physical address/ MAC address is a hardware address, which means it is unique to the network card installed on your PC. No two devices on a local network should ever have the same MAC address. In the unlikely event this occurs, the two devices will have major communication problems. During the manufacturing process, the vendor "burns" a specific MAC address into each network card's ROM. When the serial numbers have all been used, they start from the beginning, as it's very unlikely anyone would buy two network cards from the same vendor, and they will contain the same MAC address. So, to sum all that up, remember that a IP address is a logical address which is configured via the operating system, while the Physical address/MAC address is a hardware address, burnt into the network card's ROM during the manufacturing process.

Figure 6.