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‫For this tutorial, I'm going to go through the assignment of DNS Round Robin testing and you'll get

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‫to see how I would have done it.

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‫First, we need to create a network.

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‫I'm going to call it dude.

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‫Then I need to create two containers. So,

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‫I'm going to run them in the background. I don't actually care about their names.

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‫So, I'm just going to run the network and attach them to dude.

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‫And then I'm going to do a net

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‫alias so I can find them with the DNS name search.

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‫And then...

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‫there we go.

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‫Because I'm not specifying a name,

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‫I can actually just hit the Up arrow and type the exact same command again,

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‫and I should get both of those containers.

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‫I didn't open any ports because all we need to do is test inside of this virtual network.

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‫You'll notice that there's exposed ports, which we'll talk about later in the next section. But exposed

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‫ports are listed in the Docker file, and they're always exposed in the virtual network. It's only

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‫necessary to use the -p when we want to actually publish those ports to the outside interface of

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‫our host.

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‫We're not doing that here so I can skip that part.

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‫Now I need to run a test to make sure I can get to both of these with the same DNS names. So docker

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‫container run, and I'm going to do this the easy way by doing a --rm on alpine nslookup search.

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‫Oops...net dude.

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‫This should run the nslookup command on the search DNS entry and then immediately exit. Then it'll

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‫clean itself up with a --rm.

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‫All right. There we go.

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‫I have two DNS entries. For the next one, docker container run rm net

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‫dude centos curl with a -s

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‫on search

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‫9200.

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‫All right.

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‫That will get me back the Elasticsearch server named Interloper.

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‫If I run it again, I get the other one.

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‫Mr. M.

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‫You'll notice that there's also a unique ID for each one of these, and that if I hit the Up Arrow

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‫and run this command over and over, it's not exactly going to be even steven here.

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‫It's going to be a little random.

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‫You see two in a row and that sort of thing.

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‫That's just indicative of DNS Round Robin due to things like name caching and whatnot.

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‫If I do docker container...oops

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‫ls. I can actually remove these...I'm going to force them.

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‫And there we go.