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False positive
ScienceOnline
Member
in Help
Hi everybody,
I have a working vps where I have owncloud installed and it is working fine, it's online since a few months, today I can access owncloud and I can ping the ip, but since yesterday, when I made no updates nor installed anything, I got a false positive downtime from uptimerobot, I monitored thru the ip directly and I tried to change it with the domain I use and I tried to remove the monitor and recreate it, but I still get the false positive. Then I tried with statuscake and site-uptime.net but I receive the false positive even with those services.
Does anybody knows how I can investigate to understand the reason for this false positive?
I am an hobbist and I am just trying to learn how these things work, I thank you in advance.
Comments
Firewall restrictions?
Have you blocked all unknown IP Address's in your firewall and just whitelisted your own? I've done this many times accidentally!
Hello ScienceOnline!
Thanks for posting here about false positives. Firstly, to introduce myself I’m Daniel one of the cofounders of StatusCake.
False positives are no doubt infuriating and at times down right confusing but in StatusCakes operation we generally find there are a few primary causes for people to get alerts when they are not expecting them.
Firstly, as @david_reid correctly states about Firewalls are for our competitors and indeed us the biggest single reason why someone would get an alert when their site isn’t down. All website monitoring systems generally follow a pattern (checking every X minutes for example) and that pattern for a lot of firewall systems looks suspicious so in turn our test agents get blocked and your site seems down to them.
90% of the time it’s firewalls which the end user (yourself) can adjust but sometimes in very rare cases it’s the host that is running these firewalls, in which case you need to contact them.
We are StatusCake use methods that limit the chances of hitting firewalls (confirmation on other servers etc) and you can raise your confirmation server count up which would then make it even less likely.
Be aware some rubbish hosts will give you some stupid response about how they can’t unblock website monitoring services because they interfere with their performance etc. If a host ever tells you this simply close your account and never look back; bad hosts have a vested interest in making sure you can’t tell all the time your site is down!
The next single biggest reason we get for people reporting issues with a down alert is well that their site is down. StatusCake uses a geographically wide spread reporting network (100 locations globally) and the reason for that is downtime isn’t always a binary, sometimes downtime happens for a certain customer range on a certain ISP, or sometimes it happens because of geographic filters etc.
As a rough guideline around 75% of the time we get approached with a ‘false positive’ we demonstrate to the user it’s actually down and they are relived we’ve caught the localized downtime.
There is of course the chance that indeed your site was incorrectly loaded (we load hundreds of billions of URLs a year, and even if 0.0001% have an issue that is a huge number) but we limit any possible false positive with our Confirmation system; however, some users adjust this too low and in turn receive false positives.
We say each confirmation can take up to your maximum timeout, but in reality it’s nearly always much shorter so having a confirmation rate of 5 for example would work wonders.