Before migrating a domain to Amazon's Route53, we should first make sure we properly understand how DNS works
While we'll cover AWS's Route53 Domain Name System (DNS) service in the second part of this series, I thought it would be helpful to first make sure we properly understand how DNS works in general . Once we're comfortable with DNS processes and terminology, we'll explore migrating existing domains to Route53.
DNS provides a mapping between human-readable names (such as www.amazon.com ) and their associated IP addresses (such as 205.251.242.103 ). DNS is best compared to phone books where you can look up phone numbers listed by easier-to-remember names. DNS is an application layer protocol.
The user types www.amazon.com into his browser and queries the DNS server for the IP address of amazon.com. The server returns Amazon's address, so the browser can request data from Amazon's web host, which returns the elements needed to build the home page in the local browser.
How DNS Works: Domain Name System Terminology
domain name
The domain name is the human-readable name we type in the URL field of the web browser , for example, amazon.com. The Internet Corporation for Assigned Names and Numbers ( ICANN ) administers these domain names
Top Level Domains (TLDs)
A TLD refers to the last part of a domain name. For example, .com in amazon .com is the top level domain. The most common TLDs include .com, .net, org, and .info. Country code TLDs represent specific geographic locations. For example: .in for India. Here are more examples:
- com - Commercial Enterprise.
- gov - United States government agency.
- edu – educational institutions such as universities.
- org - Organization (mostly non-profit).
- mil - military.
- Network - Network organization.
- eu - European Union.
secondary domain
This is the portion of the domain name that precedes the TLD, for example, amazon .com.
Child area
Subdomains can be created to identify unique content areas of a website . For example aws for aws .amazon.com.
Domain Name Registrar
Domain registrars are critical to how DNS works by managing domain name reservations. ICANN currently allows organizations to act as domain name registrars for certain higher-level domains .
name server
Like a phone book, a name server is a collection of domain names that match an IP address.
How DNS Works: Domain Name System Record Types
a record
Address records. A records map server IP addresses to domain names. For example, 72.21.206.6 to amazon.com.
CNAME
Canonical name record. A CNAME record establishes one domain as an alias for another domain (thus routing all traffic addressed to the alias to the destination; canonical address).
Alias record
Like CNAME records, alias records can be used to map one address to another. But aliases can coexist with other records with the same name.
MX records
Mail exchange records. These records redirect the domain's email to the server hosting the domain's user accounts. Mail exchange records are used to prioritize email servers for a domain.
How DNS works
When a user types a human-readable address into a browser, the operating system's DNS client checks the information in the local cache. If the requested address does not exist, it will look for a Domain Name System server in the local area network (LAN) . When the local DNS server receives the query and finds the requested domain name, it returns the result.
If the name is not found, the local server forwards the query to a DNS cache server, usually provided by an Internet Service Provider (ISP). Since the DNS server's cache contains temporary storage of DNS records, it will respond quickly to requests. These DNS cache servers are called non-authoritative DNS servers because they provide request resolution based on cached values obtained from authoritative DNS servers .
Authoritative root nameservers maintain and provide a list of authoritative nameservers for each top-level domain (.com, .org, etc.).
The authoritative top-level nameservers maintain and provide a list of authoritative nameservers for all domains (gmail.com, wikipedia.org, etc.). Its job is to query the nameservers to find and return the authoritative nameservers for the requested domain.
Now that we have a better understanding of how DNS works, the next article will introduce you to Amazon's Route53 and show you how easy it is to migrate your existing domains to it.
Related learning materials:
https://download.csdn.net/course/detail/30340
https://download.csdn.net/course/detail/30340