01. 03. 2023
NetEye
Users often complain about long load times when trying to access IT services (Web, Citrix, Terminal Server ecc.). Also cloud services like Office 365 can be concerned. Increased load times can have various reasons – one of this reasons may be an elevated timespan needed to resolve the DNS address. To discover such problems we have implemented a new DNS plugin in the NetEye Real User Experience (RUE).
Before talking about the new plugin, let’s give a look at the single steps required for the DNS resolution. Please consider the illustration below:
During DNS resolution, the program that wishes to perform this translation contacts a DNS server that returns the translated IP address. (In practice the entire translation may not occur at a single DNS server; rather, the DNS server contacted initially may recursively call upon other DNS servers to complete the translation.
The DNS resolution is the process, which translates a DNS address into an IP address. Once the IP address is obtained, it can be saved within the DNS cache for a certain time. Another request for the same domain can be fulfilled very quickly as long as the IP address remains in the cache. When time to live expires, all steps for the DNS resolution have to be made again.
To monitor this respond times the new DNS plugin collects different information.
Some of them:
- Response Latency: elapsed time for the response
- Response Code: indicates the result code for the response (NOERROR, SERVFAIL, REFUSED, …)
- Query Type: type of requested information (A, AAAA, MX, …)
- Query Text: name to be resolved/updated
- DNS Query Class: internet/ non internet
- Answer: Carries RRs which directly answer the query
- Rec TTL: Time to live for this DNS record
- Authority: Carries RRs, which describe other authoritative servers – may optionally carry the SOA RR for the authoritative data in the answer section.
- Additional: Carries RRs, which may be helpful in using the RRs in the other sections.
- DNS OpCode: type of the action (query, update, status…)
Information recovered by Neteye Real User Experience
Detail View
Moreover, RUE allows you to graphically represent the collected data to better understand and interpret information collected.
Rappresentazione grafica
Example:
The service plus.google.com has a very low application latency (~5 ms), but the answer from the secondary DNS, which resolves the host plus.google.com comes up with elevated latency (~1.5 sec.). Users will claim low load times, but they can’t neither be assigned to the service nor to the web. They derive from DNS misconfigurations or excessive DNS utilization.
Example
Luca Di Stefano
Solution Architect at Würth Phoenix
Hi everyone, I’m Luca, graduated in electrical engineering from the University of Bologna. I am employed by Würth Phoenix since its foundation. I worked mainly as enterprise architect and quality assurance engineer. Previously I was involved in systems measurement and embedded systems programming. I have gained experience on Unix (Solaris, HPUX), Windows, and C, C + +, Java. I personally contribute to the Open Source community as beta tester and developer. During my spare time I love piloting airplanes fly over the beautiful Alps. I practice many sports: tennis, broomball, skiing, alpine skiing, volleyball, soccer, mountain biking, middle distance, none have a sample but the competition excites me! I love hiking, tracking and traveling.
Author
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