EXERCISE 3: From DNS and DHCP to Clouds and Grids

1. Explain DNS and DHCP. How does DNS differ from DHCP configuration?

The Domain Naming System (DNS) and the Dynamic Host Configuration Protocol are application layer application of the TCP/IP, or Internet protocol suite. DNS was introduced into the TCP/IP protocol suite to address the problem of the growing number of systems connected to ARPANET (pre-internet). Connection between hosts on the internet is handled by the Internet Protocol (IP). The IP protocol uses IP addresses (e.g. 192.1.1.1) to identify each computer connected on a network, and to deliver message/packets to these computers. DNS is a hierarchical naming system that assigns text-based names to be assigned to the IP addresses thus allowing clients and users to use the names to connect to the hosts rather that the IP addresses. For humans, it is far easier to remember a text based hostname, rather than an IP address. The key for DNS to work is that the IP addresses are static.

DHCP was introduced to the TCP/IP protocol suite in the late 1990’s to address the problem of maintaining IP addresses for many clients. The main premise behind DHCP is that for client-based systems connection to a network, it is not important to the client what its IP address is as it does not provide services to any computers. The clients generally only need an IP address to connect to a network to access services provided by Servers. For DHCP clients, the IP addresses they obtain from a DHCP address are dynamic.



2. Why is it important for you online business application to use a static IP address rather than have it dynamically assigned?

It is important for online business applications to use a static IP address for two basic reasons. Firstly, client systems use DNS to connect to services and DNS uses static IP addresses for its configuration. Those clients that do not use DNS will typically use some point-to-point based connections (e.g. SOAP, XMLRPC, etc.) which all use static IP addresses. In fact if all servers were to use dynamic IP address the internet would not be able to function as DNS would be unable to find hosts.

The second reason is that if an online business application does not use static IP addresses, clients will be unable to determine if the if the host they connect to is in fact your application. This would allow any one to assume the identity of your server and obtain details about your users accounts. This would be a security nightmare for online system.


3. What role can the following play in business-to-business e-commerce?
a) Private Network (VPN) or Grid computing services

A Virtual Private Network (VPN) allows businesses to securely allow their employees and trusted third parties to connect to some part of their network from the Internet. This functionality allows “road warriors” to securely connect to the business internal network when they are working offsite. It also allows IT support staff to support systems remotely.

Grid computing services allow businesses to use an untapped resource to boost performance of some application. For example a batch process can be runs across several or even hundreds computers that would normal be idle. Users who will not be using their computers for an extended period can connect their PC to the grid and allow it to be used for that batch process, or any such similar program.


b) Next generation of wireless mesh networks

Wireless Mesh networks can be used to service communities by providing wireless network facilities. Only one node in the network needs to be connected to the network for a truly wireless configuration. Wireless Mesh networks have applications in some of the following areas:

• Providing network services in “Main Street” (e.g. busy streets where businesses such as cafés and restaurants would benefit from a community supplied Internet service.
• Industrial/Commercial sites to provide Internet connections to all business with the commercial community
• Campus environments, or Campus style business environments – to provide connections to multiple buildings, and even the outdoor areas around these buildings.


c) Cloud or Social Cloud applications.

Cloud computing will allow business to provide applications as a cloud application to other business. This would allow a business which specialises in a particular business function or a niche service to provide that service to others for a fee. This benefits both parties as the purchaser may not be able to produce the service internally for the same cost due to economies of scale. Additionally, the purchaser may not have the expertise required to produce the service internally. The seller can turn their area of expertise into a marketable and profitable service.

Social clouds have the potential to allow business communities to communicate in a peer-to-peer network with like businesses about issues that are common to their particular industry. This will potentially allow industries to collaborate about issues to achieve common gaols in an open and cost effective manner.

4. If clouding computing is the ‘black box’, then grid computing is a component as the ‘white box’. Explain what you interpret about that statement.

Cloud computing can be described in “black box” terms the implementation details about the service are unknown to the users. Users really do not care about the details of the implementation of the cloud, providing that the service provides the expected outcomes for the inputs provided.

Grid computing is a network of loosely coupled computers that is typically brought together to perform some complex function. The statement referring to grid computing as a component in terms of the “white box” seems to imply that the details of the implementation of grid computing are more readily known than cloud computing. Computers that participate in the grid need to know how to join and must have the application installed that will service clients who make requests to the grid. Of course, the clients need not know about the implementation details. As with cloud computing the clients are only interested in the results of using the service.