Domain Name System

By Raul Bernardino

Introduction:

The Domain Name System (DNS) is a one of the system that transforming the host name and domain name in to the proper Internet Protocol (IP) addresses or from IP addresses translates to the resource name. Usual the internet protocol addresses are using the numeric. As human limitation it is hard to remember the IP addresses for more than 10 especially using DHCP. For example as a human being, we can’t memorize our friends phone numbers that more than 20 phone numbers, with the 10 digits numbers. We can easily remember the names of the colleagues and their addresses rather than their phone numbers. Therefore, we do have our own phone directory base on the names or addresses as a preference. This is same as in the internet protocol, we can’t remember the host IP and domain IP but we do can easily remember the host name and domain name. Each device has its own IP addresses or MAC addresses

 Mockapetris, P. (1983) “invented the Domain Name System from the original of the specifications appears in request for the comment (RFC-882). Since 1987 the publication of the RFC-1034 and RFC-1035 are an updating one of the Domain Name System specifications in which is to replace the obsolete of the RFC-882 and RFC-883.”

Domain Name System is working as follows: The domain names are consisting of parts or labels and with dots (.) as the separators. For example www.amazon.com, the top level domain is “com’, down to sub-domain which is from top level domain to left be “amazon.com”. In the older of the Microsoft windows servers’ the version was called Windows Internet Name Service (WINS). Starting from windows server 2003 the DNS becomes a part of the network infrastructure. Where, the DNS is mirrored with the active directory forests and domain.

The DNS architecture: The DNS is a hierarchical data-base distribution with set of protocols such as how to query and updates the data-base, how to replicate the information among servers, and data-base schema.

The DNS domain Names: it contains several of data including host name and domain names. It is tree structure or what so called domain namespace. The Fully qualified Domain Name (FQDN) is a unique host name among the domain names in the tree structure. Below diagram shows that mydomain is an example of FQDN.

DNS Hierarchical diagram

Therefore having a healthy DNS is important to have all communications up and running.  Otherwise it will be partial running. For example our domain is listed in spam record. We can still have access to internal emails including web browser but it is not receiving any external emails. Once our IP is release from the spam records, we will then receive again external emails.

To secure our own DNS, we do have implemented the mail filters, we called mail protectors. This software application is from the lotus notes mail protector. 

Conclusion: The DNS is an important tool in the networking infrastructure where to resolve the names in to the Internet Protocols address or from IP to the name resolve and records and updates them in the DNS data-base. It is also helping in the networks distribution points to fine the host and domain quickly.

References list:

1. Kurose J.F., Ross K.W., 2010: Computer Networking; A Top-Down Approach: 5^th Edition’; Boston, Addison-Wesley
2.  Lecture notes, CPCOMM_week2_lecture
3. DNS- Domain Name System, [on-line]. Available from: http://compnetworking.about.com/cs/domainnamesystem/g/bldef_dns.htm (Accessed date: August 12, 2011)
4.  RFC 1035 - Domain names - implementation and specification, [on-line]. Available from:  http://www.faqs.org/rfcs/rfc1035.html (Accessed date: August 12, 2011)
5.  DNS Concept, [on-line]. Available from:   http://www.zytrax.com/books/dns/ch2/ (Accessed date: August 12, 2011)
6. How DNS Works, [on-line]. Available from:   http://technet.microsoft.com/en-us/library/cc772774(WS.10).aspx  (Accessed date: August 12, 2011)