Troubleshooting Mac OS X 10.2.4: Flushing lookupd for Internet access problems

For those still experiencing Internet connection difficulties under Mac OS X 10.2.4, we have discovered that on many systems, using the Terminal command: lookupd -flushcache can result in successful connections.

The process lookupd is used by Mac OS X applications and components to look up various categories of data, typically configuration information, such as users, groups, networks, services, protocols, remote procedure calls, (RPC), mounts, printers, boot parameters, aliases and netgroups, but also DNS information.

According to Apple's documentation, Mac OS X's implementation of lookupd works through the use of agents, with each agent designed to obtain a particular type of information. For example, there is an agent for resolving DNS queries, an agent for querying the local NetInfo database and its parents, etc.

Apparently, the lookupd process and associated files can become corrupt when applying incremental Mac OS X updates, or other modifications. The Terminal command lookupd -flushcache flashes the lookupd installation and can resolve these issues in some cases.

To determine whether or not you are being affected by a corrupt or partially corrupt lookupd file, try booting into Mac OS 9 (pre-2003 Macs only) and see if host names will resolve. If they do, lookupd is a likely culprit for Mac OS X's failure to do so. Sometimes, flushing the lookupd cache can also resolve login issues.

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