SongTrellis
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Author:  David Luebbert Posted:  8/7/12; 8:14:32 PM Msg#:  5915 (top msg in thread) Prev/Next:  5914/5916 Reads:  859

DNS for Poets

Dave Winer, who through his Userland Software wrote a good deal of the software that runs the SongTrellis site, has been writing recently a series of How-tos to help folks master web technologies for themselves.

In the comments for his recent posting S3 For Poets , which explains how to setup a website for little to no cost using the Amazon S3 system, one of the folks who commented, Will Emerson, said:

"I really like what you're doing here. Helping people become producers instead of consumers is great work. I think you are going to lose people in the "THINK OF A NAME" section. You don't explain that they need a domain first and then a CNAME. The link goes to a technical explanation that will give people that glazed-fish-eye look. How about a poem about how DNS works? It's for poets, right?"

As an exercise in tech-writing I responded to Will's challenge and wrote this DNS "poem":

A domain is a political entity that responds to the rulings, wishes, and whims of a ruler. In medieval Europe, domains were entities such as an emperor's empire, a king's kingdom, a duke's duchy, a count's county, a mayor's city. In other parts of the world with other forms of political organization, the realm of control of a tribe, a clan, a warlord, or a single powerful family could also be called a domain.

In the modern world, many different organizations answer to the domain definition: commercial enterprises, educational institutions, public organizations and governmental agencies. Following the maxim from English common law that a man's home is his castle, an individual acting on his own say-so can be thought of as the ruler of his own household domain.

On the internet, domains act on the outside world by providing services. The internet's architects invented a three part naming scheme to describe all off the services that any domain might want to offer to those who have an internet connection.

The designers recognized that modern domains could be classified and decreed that an abbreviated, standard classification identifier would always be included as the suffix at the end of these three part service names. In this naming scheme, the service name coined for commercial enterprises will usually always end with a .com suffix, educational institutions will end with .edu, public organizations with .org, and governmental agencies with .gov, military units with .mil. Outside of the United States, this suffix is a country code.

The middle name of a service name is usually an easily recognized public name of an organization like google, apple, microsoft, amazon, walmart, whitehouse, wikipedia, stanford, harvard. Paired with their domain type, we recognize google.com. apple.com, microsoft.com. walmart.gov, whitehouse.gov, wikipedia.org, stanford.edu, harvard.edu as well-known internet domain names.

Any individuals or start up corporations who wish to, can coin a unique name to identify any domain that they wish to establish. As they do this, they self-classify their domain's mission to fit the .com, .org, .edu, .gov, .mil scheme. (The classification scheme has recently been expanded to accommodate new classifications such as .info, .biz and many others that are not yet in common use.)

Such persons or corporations then approach a Domain Registrar, who for a reasonable fee ($15/year seems common), will grant them usage of their chosen domain name for a certain span of time, provided no other party has previously purchased rights to that domain name. Once they have registered their name, they have rights to renew that name without interference when their initial registration expires.

For example, a group who wished to be identified on the internet using a domain named Foo that they intend to use for commercial purposes might attempt to register a foo.com domain name.

There is no limit to the number of domains that a person or corporation can establish provided they can afford the domain registration fees.

The most important function of a registrar is to provide Domain Name Service for your domain. The registrar creates a set of securely protected, publicly accessible database records, which can quickly and with ultra-reliability provide answers to any person (and more importantly, any software process) that wants to use the services that a domain provides.

The first name of the three part internet service naming scheme, describes one of the kinds of services that a particular domain offers to others on the internet. Nearly every corporate entity on earth offers a World Wide Web service that provides a way to transmit their message to any who care to read it. The typical service name given to this is wwww.

There is no requirement that www be used to identify a web service. Wikipedia for example uses en.wikipedia.org to identify the English language section of their encyclopedia.

There are domains such as wordpress.com, typepad.com, blogspot.com, blogger.com, etc. which allow subscribers to maintain their own website as unique web services accessible through their domains.

A three part name that gives one access to a particular World Wide Web service is www.amazon.com. One that I run myself on the songtrellis.com domain is www.songtrellis.com.

A website which I frequently read that is hosted by a website hosting service, John Robb's Global Guerrillas site, uses globalguerrillas as the web service name recorded in the typepad.com domain for his http://globalguerrillas.typepad.com URL.

Most domains provide a mail service that is used to contact those who are employees of the host organization that own the domain. The 'mail' service name is usually given to a domain's mail service. mail.somesite.com might be the name of the mail service that handles email for the somesite.com domain.

As the web has developed, it's been noticed that the service that an overwhelming number of requesters wish to use for a domain is the World Wide Web service. So its becoming more common to make it optional to require that a www prefix must be added to the front of the domain name to access a domain's web service. Many websites will recognize that using a domain name without specifying a service name at the beginning of a URL is actually a request to use the domain's www service.

Dave Winer's most-favored personal website by default responds to requests to scripting.com. A request directed to www.scripting.com will redirect to scripting.com.

Traffic is directed to a particular server (a computer that provides a service) via a four-part, period delimited numerical addresses called an IP (Internet Protocol) addresses. A valid IP address might be 8.8.4.4.

The currently assigned IP address for my SongTrellis site is 216.168.47.12. The URL http://216.168.47.12/ provides hard-to-remember access to my website.

Experience shows that it's nearly impossible for humans of average memory ability to remember more than a handful of numerical IP addresses. The three part names assigned to internet service names are much easier to remember.

There are special Domain Name Service servers (DNS servers) distributed around the internet, that can nearly instantly lookup the IP address that provides a particular service when they are given a three part name for a service.

A Domain Registar is responsible for providing tools that allow a domain's technical contact to maintain the DNS records for that domain. These tools are becoming easy enough to use that there is no reason that this technical contact who creates DNS records couldn't be you.

When you create a new website accessible within your own domain, you coin a new service name and create a special kind of DNS record, a CNAME, which for a particular service name records either the IP address of the computer or cluster of computers that responds to requests for that service or else records the three part human readable service name of another service that is delegated to handle those kinds of requests.

If you are setting up an S3 instance, you would create a CNAME record for a service name of your choosing that will be accessed via your domain, which will point to s3.amazonaws.com, the service name of Amazon's S3 service, which will be delegated to serve your web site.

When Amazon S3 receives a URL request that contains your service name as its first term, if you have configured S3 to associate your website service name with your own S3 bucket, S3 will use the remainder of the URL after the service name to locate and serve a file stored in your bucket as a page of your website.

When you have altered your DNS records, your registrar starts a transmission process which propagates your domains records to every Domain Name Service machine located around the web in a reasonably short period of time. This could be a day or two in worst cases.

This propagation time is actually something the technical contact for a domain determines, since each record has time-to-live parameter which declares how much time a DNS server will act on the last transmission of records for your site before it will check back with your registrar to fetch fresh copies of your records.

So the part of this S3 For Poets which talks about choosing a name for your own web service assumes that you have registered with a registrar which provides an online method for creating a new CNAME for your website which will be stored as one your domain's DNS records.

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