Welcome!

Release Management Authors: Pat Romanski, Elizabeth White, David H Deans, Liz McMillan, Jnan Dash

Related Topics: @DevOpsSummit, Linux Containers, Containers Expo Blog

@DevOpsSummit: Blog Post

Glue Records and Why They Are Crucial | @DevOpsSummit #DevOps #WebPerf

A lot has been written and discussed about Domain Name System (DNS) in the past few days

Glue Records and Why They Are Crucial
By Nilabh Mishra

A lot has been written and discussed about Domain Name System (DNS) in the past few days. The DDoS attacks on one of the major managed DNS Providers a while ago just made us all take DNS issues seriously once again.

So why so much emphasis on getting DNS Right? Like a lot of other people in this Ecosystem, we believe that DNS is not just a metric but a lifeline; a backbone for our online systems. It is extremely important to the Internet as it lays the foundation for the WWW (World Wide Web).

DNS, in simple terms, translates Host names to IP Addresses. The objective of DNS seems straight forward and simple, yet in real life, it has grown to become one of the most complex systems we have today.

All these add more complexity to an already complex system.

  • Domain Registries
  • Global Top Level Domains (gTLDs)
  • Numerous Country Code Top Level Domains (ccTLDs)
  • An ever-growing list of all the new TLDs (.space, .photography etc.)

Since DNS is not restricted to a single machine (being a distributed, coherent, and hierarchical database) and involves multiple hierarchies and entities, ensuring that every hierarchy and entity involved in managing the system is working efficiently becomes crucial. At the top of the hierarchy is:

  • Root(.)
  • gTLD servers
  • Authoritative Nameservers for domains

Every level in this hierarchy has an important role to play in the resolution process of a Domain Name:

  • The Registries (Verisign managing .COM and .NET)
  • Registrars (GoDaddy and Namecheap)
  • Registrants (those register a Domain Name)
  • ISPs
  • Managed DNS Service Providers

We all are a part of this system and it becomes extremely important for us, as Registrants, to keep an eye on how these multiple components are functioning to ensure that we have a stable and well-functioning system.

In this article, we will focus on a very important concept in DNS known as “Additional Records,” or “Glue Records.”

Additional Records or Glue Records
In simplest of terms, Glue records are A records or IP Addresses that are assigned or mapped to a Domain Name or a sub-domain. Glue records become extremely important when the Nameservers for a domain name are the sub-domains of the domain name itself.

The Glue records can be seen under the “Additional Section” of a DNS Response.

Let’s take an example to understand how Glue Records work; assume you have a domain name called “yourdomain.com” for which you are using the following set of Nameservers:

ns1. yourdomain.com

ns2. yourdomain.com

In the DNS Resolution process, the authoritative nameservers for yourdomain.com are ns1.yourdomain.com and ns2.yourdomain.com. The DNS resolution for ns1.yourdomain.com would first require the resolution of yourdomain.com, which returns the authoritative nameservers as ns1 and ns2.yourdomain.

As you may have already noticed, this creates a circular dependency, or other words a Loop, and the resolution never succeeds.

Glue records help in breaking this dependency by providing the IP Addresses for ns1.yourdomain.com and ns2.yourdomain.com in the lookup process, this breaks the loop from getting created as we no longer need to resolve the nameservers for the IP Addresses – these addresses are already provided in the form of “Glue Records”.

image2

In the example above, we see that Glue records helped remove the circular dependency by providing the A Records for ns1.ctrls.in and ns2.ctrls.in which were returned as the Authoritative Nameservers for the domain: ctrls.in. If this was not the case, the DNS Lookup would have failed because of a circular dependency.

For Domain names, which do not use sub-domains of the same domain as Authoritative Nameservers, Glue records help in reducing the number of lookups by providing the IP Addresses for the authoritative Nameservers. Here is an example for Wikipedia.com.

image1

In this case, Wikipedia.org returned ns1.wikimedia.org, ns2.wikimedia.org and ns3.wikimedia.org as the authoritative nameservers for the domain. This would have required an additional level of DNS lookup for Wikimedia.org to get the A/AAAA record for the domain name initially queried for i.e. Wikipedia.org.

One of our customers, a leading CDN provider headquartered in China, reached out to us a while ago, complaining that the A records being returned for two of their Nameservers were incorrect (Old IPs).

When investigating this case, we observed that when doing a DNS Experience test for the Nameservers, the IPs being returned by the authoritative nameservers were correct. However, when running a DNS Direct test to the Nameservers of the Domain using any of the gTLDs (a-m.gtld-servers.net.), the IPs returned were the incorrect IPs.

Digs to the domain name using the command: dig “domain name here” @a.root-servers.net returned the same response as Catchpoint’s DNS tests.

Further investigation led us to believe that this was one of those cases where the changes to the GLUE/Additional record at the Domain Registrar’s end was not pushed to the gTLD Servers.

Catchpoint DNS Monitors
Experience DNS Test For DNS tests that use the experience monitor, Catchpoint randomly selects a server from each level of the DNS route and queries it for the domain.
Direct DNS Test This test provides the complete query and response from the DNS server specified for the test along with the length of time it took to complete the test and any errors received during testing.


What fixed this issue?
Based on our recommendations, our Client reached out to the Domain Registrar for the domain and got the Glue records updated for the Domain. The change made was pushed to all the gTLD servers and the issue was resolved.

This incident emphasizes the importance of monitoring each level as well as each component of this amazingly vast system we know as DNS. Having a Monitoring strategy focused around DNS is not just recommended but is crucial to discover issues that may be under our control or out of our control.

The post Glue Records and Why They are Crucial appeared first on Catchpoint's Blog.

Read the original blog entry...

More Stories By Mehdi Daoudi

Catchpoint radically transforms the way businesses manage, monitor, and test the performance of online applications. Truly understand and improve user experience with clear visibility into complex, distributed online systems.

Founded in 2008 by four DoubleClick / Google executives with a passion for speed, reliability and overall better online experiences, Catchpoint has now become the most innovative provider of web performance testing and monitoring solutions. We are a team with expertise in designing, building, operating, scaling and monitoring highly transactional Internet services used by thousands of companies and impacting the experience of millions of users. Catchpoint is funded by top-tier venture capital firm, Battery Ventures, which has invested in category leaders such as Akamai, Omniture (Adobe Systems), Optimizely, Tealium, BazaarVoice, Marketo and many more.

IoT & Smart Cities Stories
In his session at 21st Cloud Expo, Raju Shreewastava, founder of Big Data Trunk, provided a fun and simple way to introduce Machine Leaning to anyone and everyone. He solved a machine learning problem and demonstrated an easy way to be able to do machine learning without even coding. Raju Shreewastava is the founder of Big Data Trunk (www.BigDataTrunk.com), a Big Data Training and consulting firm with offices in the United States. He previously led the data warehouse/business intelligence and Bi...
Contextual Analytics of various threat data provides a deeper understanding of a given threat and enables identification of unknown threat vectors. In his session at @ThingsExpo, David Dufour, Head of Security Architecture, IoT, Webroot, Inc., discussed how through the use of Big Data analytics and deep data correlation across different threat types, it is possible to gain a better understanding of where, how and to what level of danger a malicious actor poses to an organization, and to determin...
Nicolas Fierro is CEO of MIMIR Blockchain Solutions. He is a programmer, technologist, and operations dev who has worked with Ethereum and blockchain since 2014. His knowledge in blockchain dates to when he performed dev ops services to the Ethereum Foundation as one the privileged few developers to work with the original core team in Switzerland.
Cloud-enabled transformation has evolved from cost saving measure to business innovation strategy -- one that combines the cloud with cognitive capabilities to drive market disruption. Learn how you can achieve the insight and agility you need to gain a competitive advantage. Industry-acclaimed CTO and cloud expert, Shankar Kalyana presents. Only the most exceptional IBMers are appointed with the rare distinction of IBM Fellow, the highest technical honor in the company. Shankar has also receive...
Digital Transformation and Disruption, Amazon Style - What You Can Learn. Chris Kocher is a co-founder of Grey Heron, a management and strategic marketing consulting firm. He has 25+ years in both strategic and hands-on operating experience helping executives and investors build revenues and shareholder value. He has consulted with over 130 companies on innovating with new business models, product strategies and monetization. Chris has held management positions at HP and Symantec in addition to ...
"MobiDev is a Ukraine-based software development company. We do mobile development, and we're specialists in that. But we do full stack software development for entrepreneurs, for emerging companies, and for enterprise ventures," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
Cloud computing delivers on-demand resources that provide businesses with flexibility and cost-savings. The challenge in moving workloads to the cloud has been the cost and complexity of ensuring the initial and ongoing security and regulatory (PCI, HIPAA, FFIEC) compliance across private and public clouds. Manual security compliance is slow, prone to human error, and represents over 50% of the cost of managing cloud applications. Determining how to automate cloud security compliance is critical...
Enterprises have taken advantage of IoT to achieve important revenue and cost advantages. What is less apparent is how incumbent enterprises operating at scale have, following success with IoT, built analytic, operations management and software development capabilities - ranging from autonomous vehicles to manageable robotics installations. They have embraced these capabilities as if they were Silicon Valley startups.
Recently, REAN Cloud built a digital concierge for a North Carolina hospital that had observed that most patient call button questions were repetitive. In addition, the paper-based process used to measure patient health metrics was laborious, not in real-time and sometimes error-prone. In their session at 21st Cloud Expo, Sean Finnerty, Executive Director, Practice Lead, Health Care & Life Science at REAN Cloud, and Dr. S.P.T. Krishnan, Principal Architect at REAN Cloud, discussed how they built...
When talking IoT we often focus on the devices, the sensors, the hardware itself. The new smart appliances, the new smart or self-driving cars (which are amalgamations of many ‘things'). When we are looking at the world of IoT, we should take a step back, look at the big picture. What value are these devices providing. IoT is not about the devices, its about the data consumed and generated. The devices are tools, mechanisms, conduits. This paper discusses the considerations when dealing with the...