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Active Monitoring is the way to check the site performance by simulation of visiting by real users. It is done by external service, usually with distribyted networks. The checking servers create the requests like the real clients, who are trying to download a web page. Doing it on regular schedule, allows to check if the page is available from the web. If not - there is a possibility to catch and report the error. The difference between the bot and a real person is visible only for bulky pages with lots of content - in order to save the traffic, monitoring systems usually download only a part of such pages, which is enough to make sure the site is Ok.

Active monitoring is an independent eye on your site. The checking is not connected to your company and web hosting, and so provides the clear third-party view of the situation. HostTracker service uses active monitoring to supervise web sites.

Availability of a site shows if a site is accessible from the Internet. This term is also about access to a server, database or another entity. As all objects in the Internet are based on comlicated infrastructure, nothing can be available always. The question is how to measure it, what is normal and if we may affect it anyway. The measurement of availability is connected to terms Uptime and Downtime, which show for how long a site is unavailable. However, these values can not create the full view of the situation. There could be many reasons of unavailability - server or connection problems, application error, overload of the site and so on. To avoid or shorter the failures, it is needed to supervise the site and analyze the errors, if they happen. For these purposes there are special monitoring tools, which help to increase to availability of the site, collect statistics and provide necessary information about the errors for fast repair. These tools are called Website Monitoring services.

• CM.Glossary.Uptime
• CM.Glossary.WebsiteMonitoring

Database monitoring feature allows to run a query during every check and react in the appropriate way on the result. Also, it is possible to check just possibility to connect to DB - by ignoring the query field. To set the monitoring, fill the connection data: DB server address, port, database name, login and password of a user for connection. We strongly recommend to create the new user with limited rights. However, do not forget to provide him enough rights for performing the supposed actions. Also, it is necessary to add HostTracker servers addresses, to the whitelists on firewall or other blocking software, to allow the access. The addresses are permanent, and are listed on the same form.

There could be arbitrary query - SELECT, UPDATE, DELETE, INSERT, execution of stored procedures (like scheduler), results comparison, logical operations. The only restriction is execution time - it should not take longer than 30 seconds. Otherwise, the timeout error will be reported.

It is recommended to create the queries which display the necessary value in the first row of the first column. This result can be analysed. For UPDATE, INSERT, DELETE queries the number of affected rows is analysed. There are different ways to analyse the resulted value by comparison with specific preset - equal/not equal/higher/lower/in range. In case the condition is not satisfied, no connection to DB, query timeout - the error is reported.

Distributed monitoring is a method of website monitoring when the checking is performed from several locations. The main purpose for this is to exclude errors of checking server (which is always possible) from the site statistic and provide more precise result. Usually it is realized through the network of independent servers which check the sites one-by-one or simultaneously. The advangtages of such checks are listed below:

Checks are happening from different locations, just like the real users do.

If a single check fails - others may prove or decline the failure. So, probability of false downtimes is really low.

It is possible to overview the access and download speed from different countries and cities.

Possibility to catch network-related or DNS problems: site might be visible from your computer, but are you sure it works for everyone?

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.

Downtime is when your site does not work. If the site does not work - you'll not get any benefits from its existence. Downtime is opposite to uptime. There could be various reasons why a site does not work. Most usual cases: problems with server, server overload, application error, network problems and so on. The first step of fixing en error is detecting. There are special instruments, called website monitoring services, which may check sites for errors over the time. Such tools help you to detect error and provide primary analysis of its reasons. Also, usually some information could be found in server logs. If you have access to them, you should review. If not - ask your hosting company to provide them. Detecting of errors may help you to evaluate the reliability of your site and hosting.

HTTP - hyper text transfer protocol, a way to transfer website data via Internet. At first, was created for transfer of HTML documents, now most of website data (audio, video, images etc.) is downloaded through this protocol. HTTP has several methods - to check a website, to get the data from the server, and to upload some information from client to the site. More about them you may find in this article. HTTP has its secure version - HTTPS

This protocol is used by clients to review web pages. Thus, to check a website, we should use it too. Website monitoring services, like HostTracker, perform HTTP checks to make sure that the site is operating well.

GET method is used when the page is loaded from server to your browser. If it works, your web page is available to load. It is the most common method among all, when you type a site address in your broswer - this method is used to show you the site content.

HEAD method is similar with GET, but it load from server only headers of your page. It is useful if You want to test just accessibility of a web page or review its headers.

POST method is used to send information from you to server. If a page includes text field(s) for filling, POST method is used when you click button "submit" (or whatever is name of that button). It brings information you have typed into those fields to server. So, if there are some text fields on your page, you can use this method. If it works, your web page is available to use, and text, typed into fields on your page, is able to be transferred to the server. An example of using POST method for Website Monitoring is provided in this article (You provide specific keywords, which are inserted into text fields).

Passive Monitoring is the way to check the site performance by server-side software. It can create the exact copy of incoming traffic for analysis, or it can operate on real traffic. Passive monitoring may collect statistics and watch over some important values, like traffic consumption, number of visitors etc. Also it is handy to analyze the real workflow on your site. However, only server-side errors could be caught. If case of broken Іnternet connection or other Internet-related errors, passive monitoring fails - as it shows only the server performance which is Ok. You'll notice the the lack of visitors, but this fact does not appear immediately. And this is the main difference between the Passive Monitoring (server-side) and Active Monitoring (third-party).

Ping is request message for ICMP (stands for Internet Control Message Protocol). This protocol is used by different network devices to check if a service or a device is available. Usually it is used for network diagnostics.

Ping monitoring allows you to keep an eye on your network infrastructure. Ping failure means broken connection to a network entity. It is handy to use Ping together with HTTP monitoring. In this case, you get additional information - for example, you know if the error is site-related, or the whole server has gone down. However, sometimes ICMP could be blocked for incoming requests, in order to prevent ddos attacks.

For example you have such simple form:
form action="some-site.com/some-script.cgi" method=post
input type=text name=login value=''
input type=password name=password value=''
input type=submit name='Submit' value='Login'
/form
User fill this form with value login: Peter and password: 1234 and click submit. If everything is Ok, script prints "LoginOk" on the result page.
For making a monitoring task to control this script, create task with next fields:
URL: some-site.com/some-script.cgi
Http Method: choose POST
In "POST parameters" field you should add three strings:
login=Peter
password=1234
Submit=Login
In "Content check" field: LoginOk
Results: HostTracker with every check will fill this form and assume that it is OK if the set keyword LoginOk is returned.

1. SignUp and fill the Profile

2. Enter your sites for checking

3. Set monitoring parameters

4. Register contacts for alerts and reports

5. Subscribe for alerts

6. Subscribe for reports

7. When the Free Trial expires, subscribe to a permanent package

In case of any questions, write us to ht2support@host-tracker.com

Response time monitoring is testing how fast is your site. It might be accessible, but bad performance can still make it unattractive for the clients. The monitoring of the response time allows you to check how the site acts as the time goes on. Do any of the scheduled tasks, like backup, updates etc affect the performance? Does the site works well for the whole world, or some regions of interest could meet a confusing delay?

HostTracker provides a possibility to check the reaction of your site. Select Response time check on the main screen:

Then, select the largest satisfactory response time for the site. Is this value is exceeded, you receive a notification. Also, all the statistics is stored in the check log, and response graph is generated. You may check this data at anytime.

NOTE! Response time depends on the distance between the datacenter of your site and our checking server. It might be large enough for a remote country. To decrease this effect, select a checking region in advanced options.

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.

Web Hosting is a service which makes a site available from the Internet. It provides a physical place for your site (server) and Internet connection, also it may provide DNS services. Hosting companies differs from those who own huge datacenters to the small ones who rent couple of servers somewhere.

How to choose a hosting? You should pay attention to several important things: features, price, support and uptime.

Features include disk space, database usage, bandwidth, monthly traffic etc. Requirements totally depend on your site. It is clear that personal page has different requirements than a well-known online market.

Price. You may even find completely free hosting, just look if the service satisfies your needs.

Support. How long does it take to solve a problem with your site? What is an avarage response time? Your site is down for a week, and noone cares - is that possible?

Uptime - what is actual running time of the site.

Reliable hosting is very important for business. Using website monitoring services may help to evaluate the hosting service and check how often do the problems really appear.

Website is a single resource of information in the Internet. Usually, it is realized through a set of web pages, devoted to some specific topic. The pages are written in special markup lenguages and may contain various types of data - applications, audio and video files, images etc. The site is hosted on a hardware server and can be found in the Internet by unique name due to DNS. The access to a website usually provided by HTTP (hyper text transfer protocol), or its secure version - HTTPS. This protocol provides possibility to deliver information from the server to a client, who is usually viewing the pages with the help of special application, called browser.

Website monitoring is an automated process of checking availability of a site. The main goal of it is evaluation of possibility to access the site by clients. It is clear, that a site is efficient when an interested person can load the page and make a purchase or look for some information. If this action fails for some reason - the site does not execute its mission, and a client will find what he needs somewhere else.

There are many solutions of this problems, and all of them could be divided into passive and active ways. The result of monitoring is the value of uptime, measured with some accuracy. Having it, one can conclude how long is the site broken during some period of time (usually, for a year). Low uptime usually means that the server where the site is hosted, or internet connection to it, is unreliable and is required to be changed.