Blog Post

DNS Monitoring 101 – Troubleshoot Anycast DNS Issues

Here we look at Anycast DNS, the challenges it can present in terms of identifying which name server has answered a particular query, and solutions to them.

Today’s Tip of the Day is the final of three focused on Domain Name System (DNS) monitoring. In the rest of the series, we looked at how digital experience monitoring (DEM) can (i) help ensure users are served by the correct DNS server to reduce latency and (ii) help to guard against DNS-related attacks.

In today’s post, we talk about Anycast DNS, the advantages it provides, the challenges it presents in relation to troubleshooting DNS issues, and how to overcome them with Catchpoint.

What is Anycast DNS and What are the Advantages it Provides?

Most major DNS and CDN providers use Anycast DNS to help increase the speed of the DNS resolution process for users and improve reliability. With Anycast, one IP address can be applied to many servers. It’s a one to many relationship. Any of the related DNS servers can respond to DNS queries, and usually, the one that is closest in terms of geography will provide the request. This lowers latency, improves uptime for the DNS resolving service, and offers protection against DNS flood DDoS attacks.

Other traffic routing solutions include Unicast, a single IP to a single server, so a one to one relationship; each communication travels from one device to the targeted device on the other end of the communication. This can be problematic for a few reasons. If a routing path node becomes overworked or goes down, communication channels would be cut off. Also, individual connections between nodes and a host server can be resource-intensive.

Major DNS and CDNs use Anycast routing to distribute site content on a massive scale. Anycast HTTP request routing and Anycast DNS resolution translate into faster name lookups and file downloads, as well as increased security and redundancy if there is server overload.

Anycast vs Unicast

How to Use Catchpoint’s DNS Monitor to Troubleshoot Anycast DNS Issues

There is a downside to Anycast, however.  Since Anycast allows more than one DNS name server to share a single IP, it is difficult to tell which pool of name servers has answered a particular query making troubleshoot DNS issues a task. Luckily, with Catchpoint’s DNS Monitor, you can enable a specific nameserver lookup mechanism called DNS Name Server Identifier (NSID). NSID will retrieve information from a DNS nameserver by requesting its nameserver ID (NSID) and asking for its id.server and version.bind values. This allows you to pinpoint exactly which server has processed the request and understand where to focus your attention.

In today’s video, you will:

  • Find out more about Anycast DNS and the advantages it provides and troubleshooting challenges;
  • Watch a detailed demo of a DNS Test in Catchpoint;
  • Learn how to enable DNS Name Server Identifier (NSID) in Catchpoint;
  • Compare the performance of two different DNS servers from two different providers; and
  • Understand how to extract the actual server IDs that process each request.

Imagine trying to figure out why some users are having a poor user experience when all you have to go on is the top-level IP. Talk about finding a needle in a haystack. What’s my favorite saying? Work smarter, not harder with Catchpoint.

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