Amazon Route 53 DNS Service

Amazon Route 53 DNS Service: "

Even working in Amazon
Web Services,
I’m finding the frequency of new product announcements and updates a bit dizzying.
It’s amazing how fast the cloud is taking shape and the feature set is filling out.
Utility computing has really been on fire over the last 9 months. I’ve never seen
an entire new industry created and come fully to life this fast. Fun times.

Before joining AWS, I used to say that I had
an inside line on what AWS was working upon and what new features were coming in the
near future.  My trick? I went to AWS customer meetings and just listened. AWS
delivers what customers are asking for with such regularity that it’s really not all
that hard to predict new product features soon to be delivered. This trend continues
with today’s announcement. Customers have been asking for a Domain
Name Service with consistency and,
today, AWS is announcing the availability of Route
53, a scalable, highly-redundant
and reliable, global DNS service.

 

The Domain
Name System is essentially a global,
distributed database that allows various pieces of information to be associated with
a domain name.  In the most common case, DNS is used to look up the numeric IP
address for an domain name. So, for example, I just looked up Amazon.com and
found that one of the addresses being used to host Amazon.com is 207.171.166.252.
And, when your browser accessed this blog (assuming you came here directly rather
than using RSS) it would have looked up perspectives.mvdirona.com to
get an IP address. This mapping is stored in an DNS “A” (address) record. Other popular
DNS records are CNAME (canonical name), MX (mail exchange), and SPF (Sender Policy
Framework). A full list of DNS record types is at: http://en.wikipedia.org/wiki/List_of_DNS_record_types.
Route 53 currently supports:

•                    A
(address record)

•                    AAAA
(IPv6 address record)

•                    CNAME
(canonical name record)

•                    MX
(mail exchange record)

•                    NS
(name server record)

•                    PTR
(pointer record)

•                    SOA
(start of authority record)

•                    SPF
(sender policy framework)

•                    SRV
(service locator)

•                    TXT
(text record)

 

DNS, on the surface, is fairly
simple and is easy to understand. What is difficult with DNS is providing absolute
rock-solid stability at scales ranging from a request per day on some domains to billions
on others. Running DNS rock-solid, low-latency, and highly reliable is hard.  And
it’s just the kind of problem that loves scale. Scale allows more investment in the
underlying service and supports a wide, many-datacenter footprint.

 

The AWS Route 53 Service is hosted
in a global network of edge locations including the
following 16 facilities:

·         United
States

•                    Ashburn,
VA

•                    Dallas/Fort
Worth, TX

•                    Los
Angeles, CA

•                    Miami,
FL

•                    New
York, NY

•                    Newark,
NJ

•                    Palo
Alto, CA

•                    Seattle,
WA

•                    St.
Louis, MO

·         Europe

•                    Amsterdam

•                    Dublin

•                    Frankfurt

•                    London

·         Asia

•                    Hong
Kong

•                    Tokyo

•                    Singapore

 

Many DNS lookups are resolved in local caches
but, when there is a cache miss, it will need to be routed back to the authoritative
name server.  The right approach
to answering these requests with low latency is to route to the nearest datacenter
hosting an appropriate DNS server.  In Route 53 this is done using anycast.
Anycast is a cool routing trick where the same IP address range is advertised to be
at many different locations. Using this technique, the same IP address range is advertized
as being in each of the world-wide fleet of datacenters. This results in the request
being routed to the nearest facility from a network perspective.

 

Route 53 routes to the nearest
datacenter to deliver low-latency, reliable results. This is good but Route 53 is
not the only DNS service that is well implemented over a globally distributed fleet
of datacenters. What makes Route 53 unique is it’s a cloud service. Cloud means the
price is advertised rather than negotiated.  Cloud means you make an API call
rather than talking to a sales representative. Cloud means it’s a simple API and you
don’t need professional services or a customer support contact. And cloud means its
running NOW rather than tomorrow morning when the administration team comes in. Offering
a rock-solid service is half the battle but it’s the cloud aspects of Route 53 that
are most interesting. 

 

Route 53 pricing is advertised
and available to all:

·         Hosted
Zones: $1 per hosted zone per month

·         Requests:
$0.50 per million queries for first billion queries and $0.25 per million queries
over 1B month

 

You can have it running in less time than
it took to read this posting. Go to: ROUTE
53 Details. You don’t
need to talk to anyone, negotiate a volume discount, hire a professional service team,
call the customer support group, or wait until tomorrow. Make the API calls to set
it up and, on average, 60 seconds later you are fully operating.

 

                                                               
--jrh

 

James
Hamilton

e: jrh@mvdirona.com

w: http://www.mvdirona.com

b: http://blog.mvdirona.com / http://perspectives.mvdirona.com

 

---

From Perspectives."

Expanding the Cloud with DNS - Introducing Amazon Route 53

Expanding the Cloud with DNS - Introducing Amazon Route 53: "I am very excited that today we have launched Amazon Route 53, a high-performance and highly-available Domain Name System (DNS) service. DNS is one of the fundamental building blocks of internet applications and was high on the wish list of our customers for some time already. Route 53 has the business properties that you have come to expect from an AWS service: fully self-service and programmable, with transparent pay-as-you-go pricing and no minimum usage commitments.

Some fundamentals on Naming

Naming is one of the fundamental concepts in Distributed Systems. Entities in a system are identified through their name, which is separate from the way that you would choose to access that entity, the address that the access point resides at and what route to take to get to that address.

A simple example is the situation with Persons and Telephones; a person has a name, a person can have one or more telephones and each phone can have one or more telephone numbers. To reach an individual you will look up him or her in your address book, and select a phone (home, work, mobile) and then a number to dial. The number will be used to route the call through the myriad of switches to its destination. The person is the entity with its name, the phones are access points and the phones numbers are addresses.

Names do not necessarily need to be unique, but it makes life a lot easier if that is the case. There is more than one Werner Vogels in this world and although I never get emails, snail mail or phones calls for any of my peers, I am sure they are somewhat frustrated if they type in our name in a search engine :-).

In distributed systems we use namespaces to ensure that we can create rich naming without having to continuously worry about whether these names are indeed globally unique. Often these namespaces are hierarchical in nature such that it becomes easier to manage them and to decentralize control, which makes the system more scalable.
The naming system that we are all most familiar with in the internet is the Domain Name System (DNS) that manages the naming of the many different entities in our global network; its most common use is to map a name to an IP address, but it also provides facilities for aliases, finding mail servers, managing security keys, and much more. The DNS namespace is hierarchical in nature and managed by organizations called registries in different countries. Domain registrars are the commercial interface between the DNS registries and those wishing to manage their own namespace.

DNS is an absolutely critical piece of the internet infrastructure. If it is down or does not function correctly, almost everything breaks down. It would not be a first that a customer thinks that his EC2 instance is down when in reality it is some name server somewhere that is not functioning correctly.

DNS looks relatively simple on the outside, but is pretty complex on the inside. To ensure that this critical component of the internet scales and is robust in the face of outages, replication is used pervasively using epidemic style techniques. The DNS is one of those systems that rely on Eventual Consistency to manage its globally replicated state.

While registrars manage the namespace in the DNS naming architecture, DNS servers are used to provide the mapping between names and the addresses used to identify an access point. There are two main types of DNS servers: authoritative servers and caching resolvers. Authoritative servers hold the definitive mappings. Authoritative servers are connected to each other in a top down hierarchy, delegating responsibility to each other for different parts of the namespace. This provides the decentralized control needed to scale the DNS namespace.

But the real robustness of the DNS system comes through the way lookups are handled, which is what caching resolvers do. Resolvers operate in a completely separate hierarchy which is bottoms up, starting with software caches in a browser or the OS, to a local resolver or a regional resolver operated by an ISP or a corporate IT service. Caching resolvers are able to find the right authoritative server to answer any question, and then use eventual consistency to cache the result. Caching techniques ensure that the DNS system doesn't get overloaded with queries.

The Domain Name System is a wonderful practical piece of technology; it is a fundamental building block of our modern internet. As always there are many improvements possible, and many in the area of security and robustness are always in progress.

Amazon Route 53

Amazon Route 53 is a new service in the Amazon Web Services suite that manages DNS names and answers DNS queries. Route 53 provides Authoritative DNS functionality implemented using a world-wide network of highly-available DNS servers.
Amazon Route 53 sets itself apart from other DNS services that are being offered in several ways:

A familiar cloud business model: A complete self-service environment with no sales people in the loop. No upfront commitments are necessary and you only pay for what you have used. The pricing is transparent and no bundling is required and no overage fees are charged.

Very fast update propagation times: One of the difficulties with many of the existing DNS services are the very long update propagation times, sometimes it may even take up to 24 hours before updates are received at all replicas. Modern systems require much faster update propagation to for example deal with outages. We have designed Route 53 to propagate updates very quickly and give the customer the tools to find out when all changes have been propagated.

Low-latency query resolution The query resolution functionality of Route 53 is based on anycast, which will route the request automatically to the DNS server that is the closest. This achieves very low-latency for queries which is crucial for the overall performance of internet applications. Anycast is also very robust in the presence of network or server failures as requests are automatically routed to the next closest server.

No lock-in. While we have made sure that Route 53 works really well with other Amazon services such as Amazon EC2 and Amazon S3, it is not restricted to using it within AWS. You can use Route 53 with any of the resources and entities that you want to control, whether they are in the cloud or on premise.

We chose the name 'Route 53' as a play on the fact that DNS servers respond to queries on port 53. But in the future we plan for Route 53 to also give you greater control over the final aspect of distributed system naming, the route your users take to reach an endpoint. If you want to learn more about Route 53 visit http://aws.amazon.com/route53 and read the blog post at the AWS Developer weblog.

"