Application & system modernisation

Sharing Docker Knowledge

Our team shares some knowledge on our support site BP3 Global, Inc.

Our team is sharing some knowledge on how to address Unknown Host Errors with Docker. It's publicly available on our support site - but it also a great example of the kind of deep understanding of devOps and development issues that our team brings to the table for you, our clients. If you look at this article and it is all Greek to you, not to fear - when you have BP3 on your side you'll never be asked to read the manual, we'll always lend a hand and help you sort it.


When you install Docker on your system, it creates a default networking bridge that all containers will use by default. This default bridge uses an IP subnet of Seeing as this is at the low end one of the IPv4 Private address ranges (, it has a tendency to overlap with some some corporate subnets, like BP-3.lan. So, if you've ever fired up a container that needs to communicate with a BP-3.lan address and seen an "unknown host" (or similar) error along the way, that may be the reason why.

Containers bring key benefits:

  • Portability - it's just easier to bring a container from one host to another. (think: not installing major server software from scratch, and not having to worry much about the host operating system being different.

  • Scalability - if you isolate particular functions into containers, you can then scale those functions independently of the parts of your application that are not under stress.

  • Simple deployment - it's easy to create new instances of your application (or its containers).

  • Productivity - if done right, containers improve productivity, even allowing developers to switch between projects more easily by not having those projects installed on their host operating system (and without running the risk of installs getting polluted on a single OS).

  • Security - isolation of the application from host OS or from other major application components enhances security by hiding most internal resources from the outside world.

In the early stages, containerizing requires getting up the learning curve - but not to worry, help is available.‍

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