List Categories | List All Articles | List Articles By Title
Know How DNS Works
Domain name Servers (DNS) are an important but invisible part of the internet, and form one of the largest databases on it. Each machine on an internet is assigned a unique address, called an IP address, which is 32 bit number and is expressed as 4 octets. The method user to represent these IP addresses is known as dotted decimal Notation". A typical address looks like this: 126.96.36.199
It is very difficult to keep in mind the IP addresses of all the websites we visit daily, because it's not easy to remember strings of numbers. However, we do remember words. This is where domain names come into the picture. If you want to connect to a particular site, you need to know its IP address but do need to know its URL. The DNS gets the mappings of the IP addresses and the corresponding names.
Names and numbers
DNS converts the machine names (such as www.xyz.com) to IP addresses (such as 188.8.131.52). Basically, it translates from a name to an address and from an address to a name.
The mapping from the IP address to the machine name is called reverse mapping. When you type http://www.xyz.com into your browser, the browser first needs to get the IP address of www.xyz.com. The machine uses a directory service to look up IP addresses and this service is called DNS. When you type www.xyz.com your machines firsts contacts a DNS server, asking it to find the IP address for www.xyz.com. This DNS server might then contact other DNS servers on the internet. DNS is therefore is considered as the global network of servers. The great advantage of DNS is that no organization is responsible for updating it. It is what is known as distributed database.
The three letter codes
A DNS server is just a computer that's running the DNS software. The most popular DNS software is BIND (Berkeley Internet Name Domain) DNS is hierarchical, tree-structured system. The top is donated by'.'. And is known as the root of the system. Below the root there are seven immediate sub domain nodes and these are 'com', 'org', 'gov', 'mil', 'net', 'edu', 'Int', etc.
DNS consists of two components
This performs the task of looking up the names. Usually, there is one nameserver for a cluster of machines. If the nameserver does not contain the requested information, it will contact another nameserver. But it is not required for every server to know how to contact every other server. Every nameserver will know how to contact the root nameserver, and this in turn will know the location of every authoritative nameserver for all the second level domains.
This runs on a client machine to initiate DNS lookups. It contains a list of nameservers to use. As we have read, the function of each of these nameservers is to resolve name queries. There are three types of nameservers-primary nameserver, secondary nameserver, and caching nameserver. The secondary nameservers are configured for backup purposes. Caching nameservers only resolve name queries but do not maintain any DNS database files. It is important to note here that any change to primary nameservers needs to be propagated to secondary nameservers. This is because primary nameservers own the database records. The changes are propagated via a 'zone transfer'.
DNS uses principle of 'caching' for its operation. When a nameservers receives Information about a mapping, it caches this information .further queries for the same mapping will use this cached result, thereby reducing the search cost. The nameservers don't cache forever. The caching has a component called time to live (TTL) and the TTL determines how long a server will cache a piece of information. So when the nameservers caches receive an IP address, it receives the TTL with it. The nameserver caches the IP address for the period of time then discards it.
When a process needs to determine an IP address given a DNS address, it calls upon the local host to resolve the address. This can be done in variety of ways:
Table look up. On UNIX hosts, the table is /etc/hosts.
The process communicates with a local nameservers. This is named on a UNIX system.
By sending a massage to the remote system that is identified from the information in the file/etc/resolve.conf.
When a nameserver receives a query for a domain that is does not serve, it may send back a referral to the client by specifying better nameservers. Typically operate in the recursive manner wherein any DNS server passes requests it cannot handle to higher level server and so on, until either the request can be handled or until the root of the DNS name space is reached.
The nameservers contain pointers to other nameserver with the help of which it is possible to traverse the entire domain naming hierarchy. A host with the initial nameserver addresses has to be configured. After this, it is able to use DNS protocols to locate the nameserver responsible for any part or the DNS naming hierarchy.
Thus when a nameserver receives a request, it can do one of the following:
It can answer the request with an IP address. This method is called iterative. In this, the client simply asks the server to resolve a domain name. The server accesses its database, finds its IP address and sends that back. If the server does not find the address, it sends back an error ;DNS not found'). Contact another nameserver and try to find the IP address for the requested name. Send back a referral to the client specifying the IP address of better nameservers.
A popular user interface, called 'nslookup'is available on the UNIX system. With this, you can perform any DNS function. This program also displays the result to the user. Using is nslookup, you can obtain a listing of all the hosts in a zone. In order to do this, you first need to identify the nameserver for the zone.
The threats that are associated with the DNS are due to the lack of integrity and authenticity checking of the data held within the DNS. Also, other protocols can use host names as an access control mechanism. The internet engineering task force (IETF) has come up with DNS security (DNSSEC) extensions to DNS protocol. The main objective to DNSSEC is to provide authentication and integrity to the DNS. These are provided through the use of cryptographic'
About The Author
E-Business: Domain Names - Bad Faith
Ian McMillan registered the internet domain name TrivialPursuits.net and won the right to continue using it, after a challenge from Horn Abbot, the makers of the board game, failed to stop him using the domain name.
1-800-Get-Rich Can Toll Free 800 Number Domains Pay Off?
The toll free number 1-800-Get-Rich belongs to the Resorts Casino Hotel in Atlantic City. Perfect vanity number for a casino, right? Well apparently not.
Domain Names More Choices than You Think
When you are choosing a domain name you will probably be looking for a .com or maybe a .
How to avoid copyright infringment in your domain name
One of the most important aspects of choosing a domain name is that it should be non-infringing. This is not an easy task since most unique names have already been registered.
The Growth of ru-Domains
The registry of ru-domains reports, that the number of domain names registered in Russia's national domain, the ru-domains, has increased 19.82% in the first half of 2004 to 256.
How to Win Expired Domains
Every day thousands of expired domain names come back onto the market. This is due to the owner not extending their registration.
Investing in Great Domain Names when They Come for Sale
Domain names are not just online identities anymore they are the most important asset an online company owns. There are businesses being spun out because the owner stumbled on a good domain name.
Domain Names and Longevity
It begins as an idea -- a company name, a business venture, a personal project. You research available domain name options, choose the one you want, and finally register it.
Warning: Your Domain Name Could Infringe On Trademark Rights!
If you have or are about to purchase a domain name, YOU could be in trouble and you don't even know it yet..
Domain Name Registration and Privacy
The internet is a wonderful thing, except for a few small details. When you register your first domain name, you get your introduction to one of them.
"What's in a name? That which we call a rose, By any other name would smell as sweet" -Shakespeare (Romeo and Juliet)A rose perhaps but not your domain name!Welcome to the dotcom bubble! Here, any successful e-tailer should tell you that there's more to a name than just the name itself. This article serves precisely that purpose -against the backdrop of quality domain naming strategies and styles, auctions, speculators and court conflicts, to convince you why your online endeavor needs that perfect domain name.
How To Buy And Sell Domain Names Part Time For Profit Part 2
Let's just take a quick glimpse at what we've done so far:We've used www.wehavethem.
Aero Registrar Secura GmbH proposes to the IT departments of airports to sell aero-domains to companies at the airport. Airports can build a portal of the airport and forming by this a kind of virtual airport.
Choosing A Domain Name
--About Domain Names--Choosing a domain name for your web site is a major step for any individual or organization. You need domain names that are sticky, short, meaningful, easy to remember and at the roll of your tongue!It is very easy to choose a domain name but difficult to find a good name, simply because of the fact that most of the good domain names are taken up by organisations.
8 Million de-Domains
DENIC, the registry of the German Top Level Domain (TLD) has announced, that it has received the eight millionth application for the registration of a de-domain. The de-domain has the position as the world's favourite Country Code TLD, ahead of .
Whats In A (TLD) Name?
They're pushing for a top level domain (TLD) exclusively for porn sites. I'm quoting from this article at http://www.
How to Sell your Website
There are hundreds and thousands of websites on the internet today being bought and sold and there are many places you can sell your website such as ebay and website brokers. Though this article we will explore each of these possibilities in greater details.
The Value of a Good Domain Name
Domain names to the internet are the as necessary as wheels on a car. All websites need a domain name; it is how your website is found on the internet by your potential customers.
ICANN Registrar: za-Domains for Anybody
Why to Register md-Domains?
What is .md?.
home | site map
All articles are copyright to their owners.
Note: this website lists articles, We do not Write Articles !