We’ve announced OpenDNS CacheCheck, available at http://cache.opendns.com. If you wonder what’s in the OpenDNS cache for a domain, take a look. If you want OpenDNS to refresh its cache for a domain, use CacheCheck to do it yourself.

Background on CacheCheck

Because we’ve seen such vibrant adoption (thanks!), OpenDNS has established itself as the leader in recursive DNS services. People expect more from a leader, as they should. So, when a domain doesn’t resolve — especially one they’ve visited successfully before — users are quick to ask us “What’s wrong? Why does ‘insert-domain-name-here’ not resolve?”

We welcome these questions: our entire company is built around getting you where you want to go on the Internet as fast as possible and as reliably as possible. If there’s a problem we can fix, we want to know about it immediately.

But we’re not responsible for the entire DNS; we’re just a visible link in the chain. When a valid domain is not resolving, there are two common possibilities:

1. the domain is being moved, and the old address is still cached since the Time-To-Live (TTL) has not expired
2. the domain’s nameservers are not responding

For #1, CacheCheck lets you fix the problem immediately. OpenDNS has a huge cache to help make your Internet experience faster. OpenDNS usually holds an address for the full TTL (never longer!!). So, if a domain has been moved without lowering the TTL first, we may have the old address cached. CacheCheck, please! (groan)

We can’t do anything about #2 yet, but we can make the situation clear both to the domain owner and the would-be website visitor.

CacheCheck came from an internal tool we built to let us peek into our cache, and selectively clear it. Today, that unique functionality is available to everyone. No one else offers this kind of control and insight. You can ask any recursive DNS server for an address, but if the answer is wrong, there’s no recourse and little information.

Domain owners, especially, should find this first-of-its-kind tool valuable for domain management. Everything we do at OpenDNS is aimed at making the Internet better through DNS. CacheCheck is our first feature aimed squarely at domain owners. Fortunately, anyone who visits a website benefits, too.

P.S. Terri Wells at Devshed got some early insight into this tool for her article “OpenDNS on Mission to Improve Domain Name System” published last week. See page 4.

P.P.S. For the record, OpenDNS always suggests lowering TTL before migrating a domain to a new server. But we understand that domain migrations are not always planned, so CacheCheck can help domain owners out of a BIND (bad DNS humor).