Flushing DNS Lookups

Every now and then I run into a situation where I need to clear my DNS cache. This is sometimes needed when there are negative DNS values, meaning incorrect IP addresses on my computer for certain internet sites that I want to connect to. You can use the following commands to flush DNS and see if this allows you to reach the site.

Mac OS X:

For OS X, Lookupd takes care of cached DNS entries. You will need to open a Terminal session and type the following command:

lookupd -flushcache

On Mac OS X 10.5 Leopard, you no longer have the lookupd command. Use the dscacheutil command instead:

dscacheutil -flushcache

Windows:

For Windows, the IPConfig utility serves as an easy way to view TCP/IP settings and as a utility to flush DNS. You will need to open up a prompt and type the following command:

ipconfig /flushdns

Windows2000 & XP save negative DNS entries by default, so you might want to try disabling negative DNS caching to get a more responsive internet connection.

Microsoft has some notes on DNS settings in Windows too that you can reference.

Speeding Up WordPress

Now this may seem rather obvious, but many WordPress users enable an option that slows down postings even when the option actually warns you that this slows down postings. If WordPress just seems slow to you when you are adding content, make sure that under Options – Discussion Options – Attempt to notify any Weblogs linked to from the article is cleared and not checked. This will stop WordPress from pinging multiple websites and slowing down the posting process.

For speeding up WordPress for viewing, you need to install WP-Cache 2, which is an excellent plugin and in my opinion one of the top essential WordPress plugins.

Once your WordPress databases grow, you should definitely take the time to optimize your MySQL databses. The process is quite simple and the benefit is immediate.