What is the impact of DNS server problems in Enterprise architecture?
Team,
scenario: CLM 6.0.6 iFix004 on RedHat servers, Liberty, DB2 in Enterprise Topology (JAS with reverse IHS proxy, GC+LDX+JTS, each other app on its own server). Windows clients, predominently Firefox. Recently during intensive network usage the connection to the DNS server broke down regularly. To mitigate future effects, servers have now been switched to use a local copy of DNS server.
We noticed effects such as 15 minute requif imports taking well over 4 hours, links not showing up or being claimed to be broken. When the net was available performantly again, these effects vanished.
We noticed effects such as 15 minute requif imports taking well over 4 hours, links not showing up or being claimed to be broken. When the net was available performantly again, these effects vanished.
The question is how much of DNS calls are made on the client (e.g. browser when running ReqIf import)? Is it worthwhile considering to add all jazz servers to local hosts file on clients?
One answer
There's upside and downside to this...
If you know your servers will all have a fixed IP address then I would add them as static entries in the hosts file. It definitely speeds things up. I also run a local network between the servers internally and then have an additional external IP address assigned to the Public URI host name on your proxy - this protects your internal servers from being exposed.
If you are running virtual machines and there's any chance the IP address can change, then this can be a really bad idea, unless your virtual environment has scripting to update the static hosts file as the IP addresses change. I had this happen once in a client's environment in SoftLayer - the client had set static IP addresses and the database moved :-(
Took me ages to figure it out because they didn't mention they'd done that, but they did it for exactly the same reason you're considering it - the DNS was flakey and it caused serious performance issues. It *really* fixed the performance issue (huge improvement) until it completely broke when the IP changed.