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DNS Overview

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OVERVIEW:

Now that your site’s WP-Content and database have been brought over to the WP Engine servers, it’s time to consider how to handle your DNS setup.

This article will introduce you to what DNS is, how it’s used, and how it applies to your WordPress site on the WP Engine servers.

Please know that once you’ve configured your DNS you may use the Launch Phase within the Migration Checklist to verify that your DNS has been pointed to us; which you may find in your User Portal.

BASICS:

DNS (Domain Name System) is a system that translates names into IP addresses—and IP addresses into names. Essentially the DNS settings are what point your current (or future) website address (ie: www.yoursite.com) to the servers that host the site.

Making your site live on WP Engine will require you to point your domain registrar’s DNS settings to our servers. The actual process of pointing the DNS settings will be covered later in this Migration Process Guide.

A typical example setup would look like this:

  • A website’s domain name is “mysite.com” and this is registered with a separate company (called a domain registrar).
  • The website’s content (the photos, videos, and words) is served from the host (such as WP Engine).
  • The domain can then be set up to point to the host, so that the domain name (ie: mysite.com) will deliver the content from the host.

Below you’ll find an explanation of what is actually happening in the process of visiting a website’s address. Although there aren’t any necessary actions steps for your migration to WP Engine, the information is very helpful for understanding how the systems work.

AN INTRODUCTION:

Every computer has a string of numbers associated with it called an IP address. Computers use IP addresses in a similar way to how humans use names—computers use IP addresses to refer and connect to each other.

Let’s say a human wanted to find a computer—a computer that hosts a website, such a www.google.com. That human may be able (exclusion explained later) to type in the IP address for the computer hosting www.google.com into a web browser. That website would then appear on the end user’s screen. Most humans, however, have a very difficult time remembering the strings of numbers that make up IP addresses—we prefer to use names.

We use the term Domain to refer to the names of websites. A domain name is equal to the main name of a website, e.g. the domain for Google is google.com.

DNS (Domain Name System) is a system that translates names into IP addresses and IP addresses into names. This allows us to simply type in google.com and get to their website.

We never have to know or remember the specific IP address for Google. And if Google decides to change their IP address we need not be aware of that. We can continue to type in google.com and be assured that we will always reach the server hosting www.google.com.

An analogy for all this is the phone book. Each person in the phone book is listed by name and has an associated phone number. If I want to call my friend Jeff, I first need to know his phone number. The phone book allows me to find that phone number simply by knowing Jeff’s name. The phone book also works to keep Jeff’s phone number up to date if it changes.

HOW DOES IT WORK: 

When you sit down at your computer and to access a website, normally you will open a web browser and type in the name of a website.

The next thing that you hope to have happen is for the content of that website to appear on your computer screen. But how does the information from that website find its way to your computer screen?

Continuing with our phone book analogy, let’s pretend we want to order some food for delivery. The flow of information and food would work like this.

  1. You decide you want to order some food for delivery.
  2. You decide to order from Tony’s Pizza.
  3. You look up Tony’s Pizza in the phone book.
  4. You find the phone number for Tony’s Pizza.
  5. You dial the phone number for Tony’s Pizza on your phone.
  6. You ask Tony for some food, perhaps a nice salad.
  7. Tony asks you for your address.
  8. You give Tony your address.
  9. Tony sends over your salad.

Viewing this same process from the point of view of accessing a web site:

  1. You decide you want to go to a website.
  2. You decide to go to www.google.com.
  3. You pull up a web browser.
  4. You type in www.google.com into your web browser.
  5. Your web browser then knows it needs to communicate with the computer that hosts www.google.com.
  6. Your computer then reaches out to DNS for the IP address of www.google.com.
  7. DNS gives your computer the IP address for www.google.com.
  8. Your computer takes this IP address and contacts www.google.com directly.
  9. www.google.com obtains your computer’s IP address.
  10. www.google.com begins to send information to your computer.

11_DNS_example

ADDITIONAL DETAILS:

Sub Domain

A sub domain is a name typically assigned to a server that operates within the addressing scheme of “secondleveldomain.topleveldomain.” Probably the most familiar and commonly used sub domain name is “www”.

www is commonly the default subdomain name for a web server. In order to be valid, it must be defined and assigned among the DNS records of its parent second level domain name.

In a DNS record, a sub domain name will point to a physical server or a logical resource that appears to a web browser as a unique physical or logical server.

Examples:

  • http://video.google.com/
  • http://maps.google.com/
  • http://news.google.com/
  • http://mail.google.com/

www vs non-www

Adding www to a domain technically turns it into a sub domain. It’s very common for a domain to accept both the www and non-www version of an address, which is setup using a CNAME (explained below).

Records

We have spoken about how DNS will translate a domain name into an IP address. This information is stored on DNS servers in its cache, or within its zone files if the server is operating as the Start of Authority (SOA) for a particular domain.

The authoritative information kept inside the zone files is called “records”. There are several types of records that provide IP addresses to different types of servers. Some of the most common records are included in the Key Terminology and Definitions at the bottom of this article.

Canonical Name (CNAME) – a bit more information

This is an alias for your domain. Anyone accessing that alias will be automatically directed to the server indicated in the A record.

Example: google.example.com would redirect to google.com

Here “canonical” usually means: a more generally accepted or standard name.

This helps when running multiple services (like an FTP server and a webserver; each running on different ports) from a single IP address. Each service can then have its own entry in the DNS (like ftp.example.com and www.example.com).

The benefit of using a cname is that if the IP changes, you only have to update one record.

The downside (if it matters to the customer) is that a person could do a DNS lookup and find out that grilledcheese.com is actually hans.wpengine.com.

This sums up the DNS Overview section. You’ll find a list of key terms below and are free to move on to the next step!

Go back to the Migration Process Guide.

Key Terminology and Definitions

Glossary
DNS Domain Name System
NameServer Nameservers are the Internet’s equivalent to phone books. A nameserver maintains a directory of domain names that match certain IP addresses (computers). The information from all the nameservers across the Internet is gathered in a central registry.
IP Address A numerical address that points to a computer on a network. For example “66.72.98.236″ or “216.239.115.148″ NOTE: IP Addresses point to the web servers that may host many websites. Thus, the IP is for the server and not the website. This means that many different websites could share the same IP.
Domain Name A domain name is a unique name that identifies a website. The term domain can also refer to other unique names in the computer world, e.g. email addresses (@hotmail.com), Active Directory domains.
Host This is a computer that acts as a server for other computers on a network. It can be a web server, an e-mail server, an FTP server, etc. For example, a web host is what provides the content of web pages to the computers that access it.
Hosting The service of storing and making available all the information for a software, service, website, system, etc…
Registrar An organization or commercial entity that manages the reservation of Internet domain names.
Parking a domain Utilizing the DNS servers that are owned and operated by your Registrar (or hosting company) to be the Start of Authority for your domain/IP address.
Canonical Name (CNAME) This is an alias for your domain. Anyone accessing that alias will be automatically directed to the server indicated in the A record. Example: google.example.com would redirect to google.com.
Host or A Record The A record maps an IP address to host name.
Mail Exchanger (MX) Record This maps e-mail traffic to a specific server. It could indicate another host name or an IP address. For example, people who use Google for the e-mail for their domain will create an MX record that points to ghs.google.com.
Name Server (NS) Record This contains the name server information for the zone. If you configure this, your server will let other DNS servers know that yours is the ultimate authority (SOA) for your domain when caching lookup information on your domain from other DNS servers around the world.
Static IP An IP address that will not change.
Dynamic IP An IP address that may change over time under certain situations.