Uptime Uptime is the period of time when a site performs well.

Uptime corresponds to the time when a site is accessible from the Internet. The opposite term - downtime - shows for how long a site has not been working during specified period of time. Usually uptime is measured in percents, and for period of time is choosen year. Percents over the year could be easily transformed into time values. Some typical values of uptime and corresponding period of unavailability during the year are shown here:

90% - 876 hours

99% - 87 hours, 36 minutes

99.9% - 8 hours, 45 minutes, 36 seconds

99.99% - 52 minutes, 34 seconds

So high uptime is really important. Even if it seems that 99% is pretty high value - it corresponds to several days of failure. If that happens in a row, many clients can be lost. Uptime value is usually guaranteed by web hosting, where the site is hosted. Website Monitoring may help you to increase the uptime and check if the value, declared by the hosting company, is real.

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Service is very  reliable and performs as described in sales information.  User interface is simple and easy to use.

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Shellshock vulnerability online check
Considering the recently discovered Shellshock vulnerability, HostTracker has created a tool for testing it.
Check your server for vulnerability

How does it work?

It is developed for a Linux server with a web server installed on it. The algorithm is very simple. We consequently generate 4 http requests:

  • 1. Ordinary request
  • 2. The request tries, using vulneratility, post a "harmful" cookie which causes 2-seconds delay in respond to our special http request.
  • 3. The request tries, using vulneratility, post a "harmful" cookie which causes 4-seconds delay in respond to our special http request.
  • 4. Same as #3

Results of the test

How to understand the result?

We compare response time for all 4 requests. Three situation are possible:

  • 1. Vulnerability found. We may affirm that if the difference in responses is about 2 seconds for requests without cookie and with 2-second-delay cookie, as well as for requests with 2 and 4-second delay cookie. It means that our request was able to use the vulnerability and set these cookies.
  • 2. Vulnerability not found. All the requests have about the same response time. The cookies, likely, were not installed because there is no vulnerability.
  • 3. Uncertain situation. If the response time differs widely, without coincidence with preset by cookies delay, we can not say for sure. It could be if the server is under high load. To check this, we use two requests with same cookies (#3 and #4). If the response time for two same checks varies, we make a conclusion that the response time is not affected by cookies. At least, not only by them. So in this case our method can not detect vulnerability

Safety of checks

Our test can not damage your server. The risk consists of appearance of one extra-cookie, which is used only for our requests and can not affect normal work-flow of your site.

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Home > Glossary > DNS
DNS DNS - domain name system, a system for locating a web site.

DNS - domain name system. This system helps to find a real server by virtual site name. The system is realized by the hierarchy of DNS servers, each of them holds information about specific domains and may delegate such role to lower stage servers. Let's take, for example, site www.host-tracker.com. The upper domain is .com, so the request is made to the server, which is responsible for all .com sites. It knows where each site is located, or at least, where is another server, which knows for sure. If you get "Server not found" message, that means no record exists on the DNS server for the site name you've requested.

Each time you enter an address into the browser - a DNS request is made, in order to find where the site is located. To make this process faster, DNS data can be saved into a cache. If you own a site and decide to change its name for some reason, or if you have just created the new one - you should keep in mind that DNS cache needs some time to be updated globally. Usually, it happens within couple of hours, but it can take up to 48 hours. That's why sometimes a newly-hosted site can not be visible for some time.

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