This is the tenth and final installment In the of a ten-part series outlining the ten most common Domain Name System Records, or DNS Records. In this article I will examine the ALIAS Record. Find links to the previous articles below:
- The Complete Guide to CAA Records
- The Complete Guide to SOA Records
- The Complete Guide to PTR Records
- The Complete Guide to SRV Records
- The Complete Guide to TXT Records
- The Complete Guide to MX Records
- The Complete Guide to CNAME Records
- The Complete Guide to AAAA Records
- The Complete Guide to A Records
What is an ALIAS Record?
An ALIAS record is a virtual-record type which allow domain owners to forward their domain name to another domain name. For example, if I wanted to redirect my website blog.example.com to example.com, the path of least resistance is to add an ALIAS record. Before ALIAS records were widely available, there was no easy way to do this, since the way the Domain Name System works is looking up the root IP of a domain name and redirecting you to the nice, human-readable domain name. Since this record type is a virtual record, it is not governed under an official RFC, as they’re not officially sanctioned by ICANN.
What is the difference between CNAME and ALIAS Records?
A CNAME record does act similarly to an ALIAS record, but has limitations. For example, if
blog.jasonofflorida.com is a CNAME of
blog. cannot have any other records attached, including MX, TXT, NS or other DNS Record types. Because of this limitation, you cannot use a CNAME for aliasing your root domain. There are other limitations when using the CNAME Record though.
ALIAS Records filling the gap
The ALIAS Record was created to allow a domain name owner to alias the root domain, and to allow for an alias system that would coexist with other DNS Records. This effectively fills the gap of weakness that the CNAME Record has. The ALIAS Record easily allows you to alias your root domain to another domain name.
ADVANTAGES AND DISADVANTAGES OF ALIAS RECORDS
Using an ALIAS Record will allow for a domain to resolve more quickly than using a CNAME Record.
Each of these steps consumes several milliseconds or more, depending on network speed and conditions. This can add up to a large amount of time waiting for the final answer – the IP address. For an ALIAS Record, the query process is the same of that of a CNAME record query except the authoritative server for example.com performs steps 1 through 13 automatically—returning the final answer of an IP address. All of this means that the advantages of an ALIAS Record are Decreased time to final resolution AND the answer looks like an A record.
The disadvantages of an ALIAS Record
Queries for blog.example.net will use the location of the authoritative server of example.com, meaning that it is not possible to display geo-location information for the end user. For example, if the end user is in Miami and goes to blog.example.net (and example.com’s authoritative server’s are in Texas), then blog.example.net will think the end-user is in Texas, not Miami. If your website uses the geo-location of the end user (for example, to display local weather), then it’s inadvisable to use ALIAS Records.
How do ALIAS RECORDS WORK?
An ALIAS Record is an Amazon Route 53-specific virtual record. The name is in reference to port 53 where the DNS server requests are processed. DNS Providers like dnssimple.com and namecheap.com leverage Amazon Route 53 technology to offer ALIAS records to their customers.
Amazon Route 53 is a highly available and scalable cloud Domain Name System (DNS) web service. It is designed to give developers and businesses an extremely reliable and cost effective way to route end users to Internet applications by translating names like http://www.example.com into the numeric IP addresses like 192.0.2.1 that computers use to connect to each other. Amazon Route 53 is fully compliant with IPv6 as well. Amazon Route 53 effectively connects user requests to infrastructure running in AWS – such as Amazon EC2 instances, Elastic Load Balancing load balancers, or Amazon S3 buckets – and can also be used to route users to infrastructure outside of AWS. – Amazon Route 53
Alias records act similarly to CNAME records but are resolved on the server side and appear to clients as an A record…because alias records are resolved on the server-side and return A records to clients they can be used in domain apex records in a similar way to a CNAME record, where CNAME records are disallowed for this use by – wikipedia
How to Add an ALIAS Record
Not all providers support ALIAS records, NameCheap, DNS Simple, and EasyDNS are three hosting providers that do allow for the ALIAS record. To Add an alias record:
Loginto your DNS provider and select
ADD NEW RECORD
- Set the field values as follows:
- Record Type:
@– this indicates the domain name you’re actively managing the DNS for
EXAMPLE.COM– this represents the domain name you want to set as an alias for your present domain.
- Record Type:
It may take a few minutes to globally propagate to all the servers, you can check the global propagation by going to WhatIsMyDNS.net and querying for the A Record of your domain.
If you received some added value from my post, please like and follow us on Facebook, Twitter, and LinkedIn, or subscribe to jasonofflorida.com. Next in the DNS Records Series I will discuss the ALIAS Record.