Domain Name System, Essay Example

Introduction

Domain Name System (DNS) relates to an “industry suite of protocols that incorporate TCP/IP” (Microsoft TechNet). You implement DNS by the use of two key software components (i) DNS Server and (ii) DNS Client. These may be considered as background service applications.  In the Context of TCP/IP DNS consists of both the TCP/IP model [split into four distinct layers – Application layer, Transport Layer, Internet Layer and Network Office Layer]. The Protocol suite is split into TCP and UDP which embraces network considerations like that of Ethernet, Token Ring, Frame Relay and ATM. Fig 1 refers.

Figure 1: DNS in TCP/IP

The DNS may really be considered as a database of host information.  The distributed database has an indexing system by domain names which are essentially a hierarchical tree structure.  You will observe in Fig 2 that it has a large node at the top of the structure and this is called the root directory. The “depth of the tree is limited to 127 levels” (Paul Albitz). This hierarchical structure has a strong resemblance to that of the UNIX operating system file structure.

The development of DNS from an historical perspective was to support the tremendous growth of E-Mail and the internet. “Alphabetic host names were introduced on the ARPANET” (Postel).  Arpanet increased the concept of using alphabetic names and as such increased the ease of addressing; as opposed to previous useless numeric references. It was in the 1980’s where recognition was made to the disadvantages of centralized management and large dynamic amounts of data.  This triggered a re-examination into how e-mail was handled. Hence domain names were created in order to provide each individual with a unique name and address and as such provide absolute addressing.

Figure 2 Structure of DNS Name Space

Microsoft’s implementation of DNS

Microsoft made the first significant implementation of DNS on its’ Windows 2000 Operating system. “DNS is a distributed database that contains mappings of DNS domain names to data. It is also a protocol for Transmission Control Protocol/Internet Protocol (TCP/IP) networks, defined by the Requests for Comments (RFCs) that pertain to DNS.” (Microsoft TechNet). Windows users essentially want ‘plug n play’ software and as such “We live in a modern age where many information technology users demand mobility and freedom. Microsoft Windows users in particular expect to be able to plug their notebook computer into a network port and have things “just work.” (Samba).   DNS is therefore a system of name servers where the computer stores information on network resources, names to IP mappings and database files. These are stored in a hierarchical structure where the database stores the ISP addresses e.g. “Microsoft.com”, “Stanford.edu” etc.

The Microsoft DNS server was designed with the purpose of handling all DNS needs. In particular replacing the awful WINS server that troubled Microsoft Windows users for so long. The Windows 2000 active DNS server worked in harmony with domain controllers to improve active directory resources. “Microsoft DNS server is a new service in the family of TCP/IP networking services provided by Windows NT Server version 4.0. It enables you to provide and manage DNS services for your private TCP/IP networks and for users who connect to the public Internet.” (Microsoft).

Merits/problems with Microsoft implementation of DNS

Problems

Microsoft experienced a number of problems or issues with the implementation of DNS. One of these related to the fact that the SPF and sender ID are not the same. “They differ in what they validate and what “layer” of the e-mail system they are concerned with. Sender ID is not the latest version of SPF – it is a new and independent experiment” (Mehnle).  In 2007 Microsoft stated that they were aware of the problem and had no immediate plans to fix it. Some problems have existed with compatibility issues between the different versions of windows, for example “A problem occurs with our Service Desk personnel that have Windows XP based systems” (Crockett).

Merits

The merits of Microsoft DNS implementation may be briefly summarised as follows:

• The Microsoft DNS server is fully compliant with internet standards;
• Fully compatible with BIND – Berkeley Interface Name Domain;
• Uses the same resource records and zone file structure  as other DNS servers;
• Improved levels of integration with Active Directory Replication services;
• Facilitates easy additions of new servers to improve system architecture;

Fig 3 Illustrates a typical DNS internet server.

Works Cited

Crockett, Merton Campbell. Microsoft’s nslookup Implementation Problems. 13 6 2010. 15 9 2010 <http://www.pubbs.net/201006/bind/23649-microsofts-nslookup-implementation-problems.html>.

Mehnle, Julian. SPF vs. Sender ID. 11 6 2007. 15 9 2010 <http://www.openspf.org/SPF_vs_Sender_ID>.

Microsoft. Managing MS DNS Servers. 2010. 15 9 2010 <http://www.microsoft.com/resources/documentation/windowsnt/4/server/reskit/en-us/net/sur_dns.mspx?mfr=true>.

Microsoft TechNet. Introduction to DNS . 2010. 16 9 2010 <http://technet.microsoft.com/en-us/library/cc958978.aspx>.

What Is DNS? 28 3 2003. 16 9 2010 <http://technet.microsoft.com/en-us/library/cc787921(WS.10,printer).aspx>.

Paul Albitz, Cricket Liu. DNS and BIND, 3rd Edition. 1998. 16 9 2009 <http://oreilly.com/catalog/dns3/chapter/ch02.html>.

Postel, J. Domain Name System (DNS) History . 8 2 1982. 16 9 2010 <http://www.livinginternet.com/i/iw_dns_history.htm>.

Samba, John H. The Samba Team. 2010. 16 9 2010 <http://www.samba.org/samba/docs/man/Samba-HOWTO-Collection/index.html>.

Figure 1: DNS in TCP/IP. 1

Figure 2 Structure of DNS Name Space. 1

Figure 3 Internet DNS Server 3