The Learning Activity titled “What Are Network Protocols and Network Services?” informs that the concept of a network service refers to the application that operates at the level of the network. The two examples of network service are the Domain Name System (DNS) and the Dynamic Host Configuration Protocol (DHCP). The DNS role is to convert the domain name into numeric Internet addresses (IP addresses). DNS is one of the “largest name services in operation today” (Mockapetris and Dunlap, 1988, p. 123). The task of the DHCP is to assign IP addresses to the network hosts. Another example of a network service mentioned in the reading is email server because the exchange of letters via email is impossible without the permission of users to access the incoming information.
To identify the network services that you will use on the network, a network administrator should, first of all, determine the purpose and the expected outcome. More precisely, there are several types of network services, including file management, remote access, configuration, and print services. Therefore, it is necessary to understand for which purposes a network service is needed. Besides, it is also essential to determine the scale of network service: a local level or a level of general Internet communication.
The hierarchy of a DNS name consists of four levels: root, top-level, second-level, and subdomain. Even though DNS names are not numbers, as in the case with IP addresses, they must be unique to operate. It is impossible to change the hierarchy of a DNS name because otherwise, the DNS name would become useless. Still, changes are possible within domains that constitute the hierarchy of a DNS name. For example, the top-level domain identifies the location or type of organization and, hence, the website shifted from being a commercial entity to a non-profit entity; this will be reflected in the DNS name because com will be replaced with org.
Reference
Mockapetris, P., & Dunlap, K. J. (1988). Development of the domain name system. In Symposium proceedings on Communications architectures and protocols (pp. 123-133).