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Category: Network Services Monitoring

Caffeinated DNS Monitoring and the AT&T DNS Outage

To Cache or Not-to-Cache – that is the DNS Monitoring Question

Firstly, it is not generally well-known that external-based HTTP request-type website monitoring, like coffee at your local java joint, comes in different “grades” – cache-based and non-cache based. Dotcom-Monitor employs non-cached monitoring, which propagates through the full DNS process with each monitoring instance. Cache-based monitoring (used by many basic monitoring services) does not propagate through the DNS process and misses DNS issues.
How to Effectively Monitor for the next DNS Outage Situation

In the case of the AT&T DNS outage issue there are several key factors that help to speed up Time-to-Repair (TTR), or avoiding downtime.

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Doing DNS Monitoring Right: The AT&T DNS Outage

Doing DNS Monitoring Right: The AT&T DNS Outage: The AT&T domain name server (DNS) outage of Aug. 15, 2012 exemplifies why a “non-cache based” method for monitoring of websites is important for mission-critical websites. Firstly, a bit of a review. The most common, basic form of website monitoring is conducted using a synthetic browser (not an actual browser), which connects to the target server via an HTTP request process. A number of server-focused processes, such as the availability of the target server, the time it takes to load the HTML file for the website from the server, and the capability to detect keywords within the HTML file are checked via the use of a synthetic browser using an HTTP request process.

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DNS Diagnostic: Update on the ATT DNS error

August 15, 2012-The ATT DNS outage demonstrates the importance of real-time root cause diagnostics when monitoring Internet services. Intermittent ATT DNS errors were first detected at 5:23 AM PST by Dotcom-Monitor a full hour before AT&T reported the issue. The Dotcom-Monitor Minnesota node noted the issue and captured a diagnostic DNS trace at the time of error. Non-clients of Dotcom-Monitor can use a free DNS trace tool here to test if their domain is affected by selecting Trace Style “DNS”.

This piece of info was sent immediately to Dotcom-Monitor clients whose services were affected by the ATT DNS outage. This diagnostic gave Dotcom-Monitor clients immediate info that pinpointed the root cause of the issue without the need for additional troubleshooting. Dotcom-Monitor clients using ATT DNS made extremely fast, informed decisions, such as moving their DNS to another provider, or taking alternative measures to re-route traffic.

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System Status Update: DNS Error Issue | Zerigo DNS services

Starting at around 06:00 AM CST, July 23, 2012 Dotcom-Monitor began to detect a higher than usual number of DNS-related errors. The errors were sporadic and happening in bursts every couple of hours.

We are still looking for a root cause, but we believe issue started with a DDoS on Zerigo DNS services. We have a large number of our clients using Zerigo for their DNS hosting. Zerigo took their servers down due to the DDoS DNS this morning.

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Level 3 Communications Backbone Connectivity Issue

Aug 1, 2011 – Some Dotcom-Monitor clients may have experienced alerts due to a Level 3 Communications connectivity issue. For details see the statement below from Level 3 Communications explaining the event and the resolution.

“Much of the internet connectivity in and to the Continental United States was degraded by an outage within the Level 3 Communications backbone that began at approximately 17:22 1 August 2011 UTC. The impact of this event was felt not only on the Level3 backbone but also on other carriers as providers shifted large amounts of traffic that would have normally transited the Level3 network onto alternate network paths, causing increased latency and congestion and packet loss.”

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IPv6 Performance Monitoring: An External View on June 8, IPv6 Day

External IPv6 Monitoring for IPv6-Enabled Services

As highlighted by the upcoming IPv6 Day on June 8, the need for a new Internet Protocol (IP) is well understood and accepted in the networking industry.

Requirements for more address space, simpler address design and handling at the IP layer, better Quality of Service (QoS) support, greater security, and an increasing number of media types and Internet-capable devices have all contributed to drive the development of Internet Protocol version 6 (IPv6).

What is less well understood certainly are aspects of how external monitoring helps identify key challenges for businesses using IPv6, specific areas for IPv6 performance monitoring, and the benefits of external IPv6 performance monitoring. Firstly, for brevity sake are some of the basic aspects of IPv6-related monitoring are noted in the grid below and the services to test and monitor. Then, a longer, detailed notes on the aspects of IPv6 as related to external monitoring.

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IPv6 Monitoring | IPv6 Performance, Network & Security Monitoring

The switch to IPv6 is jumping to light speed. On June 8, 2011 several large organizations, including Google, Yahoo, and Facebook will run a comprehensive test for switching to IPv6. If all goes well most companies will start making the switch. However, the advent of IPV6 is not without problems and the performance monitoring solutions that worked for IPv4, will not work with IPv6.

Using an active external performance monitoring service will be critical with the advent of IPv6. Network and website managers must have a true view into end-user connectivity and the ability to receive instant notification whenever a problem occurs. For instant free test tools for IPv6 performance see ServerView Monitoring™ https://www.dotcom-monitor.com/free-uptime-performance-tests.aspx™ https://www.dotcom-monitor.com/technical-tools-browser-test.aspx .

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