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Showing posts from August, 2014

dns resolver behavior

i had an occasion to have to look up windows client behavior when it came to dns. specifically, i wanted to know how the client behaves when the primary name server is offline. before i had to fire up packet trace and check for myself, i stumbled on a couple of useful articles that spell it out.UPDATE: had a conversation with a talented linux dns guy and discovered a few more useful things to note.dns client resolver behavior
dns client resolution timeouts
dns forwarders and conditional forwarders resolution timeoutsin summary, it works as follows:dns query sent to preferredif no response within 1 second, dns query sent to alternateif no response within 1 second, dns query sent to preferred againif no response within 2 seconds, dns query sent to preferred and alternateif no response within 4 seconds, dns query sent to preferred and alternate againif no response within 7 seconds, process times outsomething to note for linux systems, these appear to be default values:timeout:n
sets the amo…

troubleshooting wmi…

this exhaustive series on troubleshooting wmi from the ask the performance team blog is too good to pass up. use of wmi is pervasive, guaranteeing that just about all of us have run into wmi issues at some point or another. if you haven’t yet, it’s only a matter of time. might as well do your are the topics the series will be covering:WMI: Common Symptoms and Errors WMI: Repository Corruption, or Not? WMI: Missing or Failing WMI Providers or Invalid WMI Class WMI: High Memory Usage by WMI Service or Wmiprvse.exe WMI: How to troubleshoot High CPU Usage by WMI Components WMI: How to Troubleshoot WMI High Handle Counti’ve blogged a few times about wmi myself: