Ask an OpenShift Admin Office Hour - DNS and cluster networking

DNS forms the backbone of service discovery, both internally and externally, with OpenShift. Did you know OpenShift has separate DNS for Pods and nodes? This episode we’re joined by Christian Hernandez, DNS expert and Technical Marketing Manager for OpenShift, to talk about how DNS is used and configured for both Pods and nodes in the cluster. We also discuss external DNS resolution and how to configure forwarders using the OpenShift DNS Operator.

As always, please see the list below for additional links to specific topics, questions, and supporting materials for the episode!

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Episode 23 recorded stream:

Supporting links for today’s topic:

• Use this link to jump straight to where we begin talking about DNS in OpenShift.
• OpenShift uses CoreDNS to resolve queries from Pods.
• Documentation for the OpenShift DNS Operator.

Other links and materials referenced during the stream:

• A couple of OpenShift on VMware bugs have come to my attention the last week or so that are important for you to be aware of: 1) BZ1883993 - deleting an IPI worker node that is inaccessible to OpenShift can result in any attached PVCs also being deleted, and 2) BZ1935539 - packet loss after upgrading to OCP 4.7 when using vmxnet3 NICs.
• In case you missed it, we recently published a blog post on sizing applications in OpenShift. You can hear us discuss on the stream here, where we also reference several other Ask an OpenShift Admin live streams: Episode 15 - Sizing OpenShift clusters and nodes, Episode 12 - Storage for Pods, Episode 10 - Storage for Nodes
• Reference architectures can be a bit of a sensitive topic. Lots of people want them for a myriad of reasons, but Red Hat stopped producing OpenShift reference architectures in the 3.10 timeframe. However, that doesn’t mean we forgot about them! Instead, our partner ecosystem has taken the mantle and creates reference architectures for their hardware or software platform. For example, you can see HPE, NetApp FlexPod, and even VMware reference architectures for OpenShift all on their own websites.