Computing 205/406 & IT8

Tutorial #7

1. The following are some (possibly hypothetical) IP addresses:

   205.184.10.20	48.55.190.88	10.170.45.56
   149.144.20.82	192.54.252.7	128.250.150
   

   Extract the network number and the host number from each of these, stating what class of network it is. Note that the last one is not a typing error.

2. What[1] is the chief difference between the IP addressing scheme and the International (and Australian) telephone numbering scheme?

3. One of the weaknesses of the IP addressing scheme is that when a machine is physically moved from one network to another, its address must change. Why is this so, and why is it a problem?

4. We have seen that the address with all 1�s in the host part is used as the IP broadcast address. What do you think the address with all 0�s in the host part is used for?

5. The class-B networks in Q.1 are to use subnetting, with a netmask of 255.255.255.0. What are the subnet and host parts of the addresses? What is the broadcast address in each case? (Harder) What if the netmask were 255.255.255.128?

6. We have seen the broadcast address format where subnetting is used. What happens if the system administrator makes a mistake, and doesn�t set up subnetting correctly on one of the hosts in a subnet?

Practical exercises:

• You can use the nslookup or dig utilities to discover the IP addresses of hosts. Use one of these to discover the IP address of some Internet hosts, as in:

  nslookup redgum.bendigo.latrobe.edu.au