Why would ipconfig /release then /renew "fix" an apparent DNS client issue

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http://serverfault.com – I seem to be having DNS issues --- which I suspect may be client related. At seemly random intervals, name resolution of local FQDN names fails. There's a warning in the system log: Name resolution for the name xxxxxxxx.yyy.zzz timed out after none of the configured DNS servers responded. (name redacted) If I do ipconfig /release and then ipconfig /renew then all is fine, until the next random occurrence. This is a very small network, with a Windows 2008 (SP2) standard running Active Directory + DHCP + DNS. My workstation is Windows 7 (SP1) We're on the same physical network, with a net (HowTos)