Loading content/resolver.rst 0 → 100644 +42 −0 Original line number Diff line number Diff line Testing DNS with a clean cache ############################## :date: 2016-11-01 :summary: Testing DNS with a clean cache Every so often I make changes to a DNS record, test it, find out it's wrong, fix it and still get the old response because of caching somewhere along the line. After it happened to me and a colleague during a launch of a new version of a website, I decided to address the issue. I wanted a way to test DNS quickly and easily (preferably locally on command line), for it to be lightweight, doesn't require changes to my existing setup and doesn't require learning new tools. I decided to create a Docker image that has its own DNS resolver and each new container from that image has a clean cache and doesn't depend on other DNS servers or is affected from their caching. Usage ----- To create a new container: .. code:: shell docker run -it adarnimrod/resolver Inside the container you have access to :code:`nslookup`, :code:`dig` and :code:`mail` for testing purposes. If you need to test new changes, :code:`exit` the container and create a new one with no cache. If you want to run just a single command (like getting the MX record for :code:`shore.co.il`): .. code:: shell docker run adarnimrod/resovler dig +short shore.co.il mx How does it work ---------------- On launch, the container runs and uses its own DNS resolver (in this case NSD). This way the OS caching or upstream caching interferes with querying and every new container starts with a clean slate. Loading
content/resolver.rst 0 → 100644 +42 −0 Original line number Diff line number Diff line Testing DNS with a clean cache ############################## :date: 2016-11-01 :summary: Testing DNS with a clean cache Every so often I make changes to a DNS record, test it, find out it's wrong, fix it and still get the old response because of caching somewhere along the line. After it happened to me and a colleague during a launch of a new version of a website, I decided to address the issue. I wanted a way to test DNS quickly and easily (preferably locally on command line), for it to be lightweight, doesn't require changes to my existing setup and doesn't require learning new tools. I decided to create a Docker image that has its own DNS resolver and each new container from that image has a clean cache and doesn't depend on other DNS servers or is affected from their caching. Usage ----- To create a new container: .. code:: shell docker run -it adarnimrod/resolver Inside the container you have access to :code:`nslookup`, :code:`dig` and :code:`mail` for testing purposes. If you need to test new changes, :code:`exit` the container and create a new one with no cache. If you want to run just a single command (like getting the MX record for :code:`shore.co.il`): .. code:: shell docker run adarnimrod/resovler dig +short shore.co.il mx How does it work ---------------- On launch, the container runs and uses its own DNS resolver (in this case NSD). This way the OS caching or upstream caching interferes with querying and every new container starts with a clean slate.
