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RE: Wildcard DNS



I'm sorry. Ow, I was wrong there.
I've edited like this: It's working but it's very slow (but that's maybe normal?):

52.18.247.58 jenkins.apps.evolane.com myphp.apps.evolane.com sample.apps.evolane.com ruby.apps.evolane.com wordpress.apps.evolane.com influxdb.apps.evolane.com grafana.apps.evolane.com test.apps.evolane.com sample.apps.evolane.com


Subject: Re: Wildcard DNS
To: lorenz vanthillo outlook com; users lists openshift redhat com
From: flozano redhat com
Date: Tue, 27 Oct 2015 11:40:43 -0200

Hi Lorenz,

Please keep discussion on the list for all to benefit. Click "Reply All" on your e-mail client.

Now my file (/etc/hosts) looks like this:
52.18.247.58 jenkins.apps.evolane.com myphp.apps.evolane.com sample.apps.evolane.com ruby.apps.evolane.com wordpress.apps.evolane.com influxdb.apps.evolane.com grafana.apps.evolane.com test.apps.evolane.com sample.apps.evolane.com

This is what the ping is doing:

my-MacBook-Pro:~ name$ ping myphp.apps.evolane.com
PING jenkins.apps.evolane.com (52.18.247.58): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1

So It's redirecting to my jenkins.apps.evolane.com (which works as only one because it's first in the line in /etc/hosts)


No it is not redirecting. It is working as expected and if you your routes are configured and applications are running it should work just fine.

Ping first resolves the FQDN you gave to it (myphp.apps.evolane.com) and sends ICMP requests to the resolved address (52.18.247.58). Remember that for TCP/IP only IP addresses matter, they have no knowledge of host names and FQDNs.

Then, Ping tries a reverse resolution on the IP address, and if this returns multiple FQDNs it shows only the first one. That's why you see "PING jenkins.apps.evolane.com". It is NOT pinging the name jenkins... but the IP 52...

Ping does this reverse resolution in an attempt to show the "physical" server host name in case the same machine (actually the same IP address) answers for multiple names. But ping has no way of knowing which of the multiple names is the actual machine name. It may not even exist a "physical" machine involved, but the ping utility was created before there was virtualization and containers. ;-)

How the OSE router knows wich application redirects the packets, all all of them go to the same IP address? The HTTP protocol sends the complete URL of the requested page, so HTTP tells which hostname is expected. Using this information OSE can direct packets to the correct application. Thanks to HTTP you can have things like a reverse cache in front of multiple sites, or a security appliances that detects Cross-Site and SQL injection attachs, or a load balancer, or anything you want and still be able to direct packets to the correct machines, VMs, containers or applications.


[]s, Fernando Lozano


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