How to check DNS 'health'?

Hi everyone,

I've got a simple, stupid question that I'm sorry to clutter the forum with - unfortunately, I don't know the answer, or know who to ask!

Last night for some reason Google and all related services went down for me, and I can verify, most other people using the same ISP in a close area around me. The rest of the web was accessible - it was only Google that gave us problems. This morning, things are working again - But GMail seems very sluggish. Logging in to GMail (via bookmark) seemed okay, if slow, but it gave me weird messages upon logout. I clicked to log out of my account, and got a message about how I had been logged out because someone on another computer had logged into my account - Strangely, I logged back in immediately, and didn't see any unfamiliar IPs in my record log.

My long winded question is, how do I check to ensure my DNS server is still pointing me toward the right Google services? Since I saw the same 'blackout' and slow access across multiple computers (Windows, OS X, and Linux), the only thing I can think of that might be happening is a DNS hijack to point all these various machines to a malicious 'phishing' version of GMail. However, I have no idea how to verify if my DNS server is 'healthy' or 'poisioned'. Thanks for any help!

 

https://www.grc.com/dns/dns.htm might be useful.

If you know the IP you should be going to you can command line "nslookup" then the domain name.

 

http://www.dnswatch.info/
http://www.robtex.com/dns/
https://www.dns-oarc.net/oarc/services/dnsentropy
http://downforeveryoneorjustme.com/
http://centralops.net/co/ (use NsLookup utility)

 

Thank you both very much. These links are extremely helpful! I appreciate it.