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.

  • CM.Glossary.WebsiteMonitoring
  • CM.Glossary.Uptime
  • CM.Glossary.WebHosting
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HostTracker is reliable and very useful to me and my team.

"
- D.
What could we check by using the cloud services? Part 2

  In the beginning, HostTracker company was founded on the basis of a simple website to provide free customer services. Though, a few years later, this startup developed a wide variety of tools serving to solve various problems, including different network issues. In a series of publications, we have decided to describe thoroughly all the features of our service, also to share our experience in the development of such projects with you and to mention interesting challenges that we faced. 

In the beginning, HostTracker company was founded on the basis of a simple website to provide free customer services. Though, a few years later, this startup developed a wide variety of tools serving to solve various problems, including different network issues. In a series of publications, we have decided to describe thoroughly all the features of our service, also to share our experience in the development of such projects with you and to mention interesting challenges that we faced. Moreover, for those seeking an example of how to sell something that had been made for themselves, our experience would be useful, as most of our features were developed due to our personal needs.

In the previous part of the review we have talked about the history of the service and the most basic functions - regular inspection of sites and servers, and what is more, notification of their efficiency. Before starting to describe more advanced features, we should write where do all these ideas come from and how to prioritize them. One of the key secrets often used by entrepreneurs is to follow the statement: all people are unique. All customers’ requests are unique, so you have to learn how to deal with them. Therefore the IT sector is utterly susceptible to this factor, as a great number of customers have profound knowledge and diverse experience. Nevertheless, part of the problems can be solved with available resources. However, the main feature of our work is that, frequently, we have to evolve something. Most of the HostTracker’s functions were developed or adapted due to the conveniences and needs of the particular people. We are also a part of that people, as having rather large infrastructure, and also need to have everything work properly. Therefore, we ourselves are the most picky client.


Precious little things

It worth noting, that in addition to different regular checks, there are other useful tools. They include monitoring of the domain and SSL certificate expiration time. This seems to be negligible, but could bring a lot of unexpected inconveniences to work. These functions appeared in HostTracker, when one of our personal domains had expired. Moreover, large companies also frequently face these problems, as the prolongation of the domain /certificate expiration time depends on the unreliable human factor. Therefore, a notification that the domain should be prolongated, is stored not only within spam folder (already overflowed with continuous marketing messages from your hosting company), but also to the folder with the data of website downs. As well as, the SMS notification capability still exists. That’s why these features are being so handy.

Another interesting feature is the domain check to see if they are blacklisted in DNS-based lists. These lists are independent and are generated separately using different algorithms. What is more, they were mainly created for filtering of the suspicious entities. Each administrator can configure own web server in different ways, for example, not to receive messages from the servers from a specific list. It helps fight off spam, malware spread, DDoS attacks and other problems. But all of these lists have their own algorithms, and there is no guarantee that in the result of any coincidences your website wouldn’t appear in any of these blacklists. Moreover, according to the statistics, this is happening on a regular basis with the most innocent sites. For example, no one can guarantee that a hacker wouldn’t use your nearby IP for different spam attacks. In this situation, the entire range of IPs would be considered as unreliable. What are the consequences of that?  Your messages wouldn’t be delivered to customers, the site wouldn’t be so easily found in search system and so on. Furthermore, you will find out this problem when the changes become critical or even irrevocable. Therefore, the monitoring and notification of DNSBL are also essential.

The content check

Here is a good example of how the usage of functions may exceed developers expectations. We have mentioned about several such cases earlier. Actually, nowadays a lot of things have a web interface whilst for others – it could be easily created, if needed. Therefore, it was developed not only the check function of whether the page was loaded completely using simple parsing, but also another mind-boggling things of this check. Adapting to different customer requests, this feature has become very flexible. It may look for one or plenty of words from the list at once. Moreover, it may detect the emergence of certain phrases. This feature may also raise as an error the whole line that contains the keyword. For instance, if there is a kind of server-status page (“Server 1 OK” etc.) and it shows “Error”, then the message will be “1 Server Error”.  In this case, all diagnostic is already done, and you can start troubleshooting immediately.

What if it happens, that the server should be down?

In addition to the notification of the failures of the sites, HostTracker provides another important function – gathers statistics of each examined site. When the various buttons on the sites were popular – HostTracker’s button also often appeared with the figures of website attendance, the weather forecasts and other things like that. Now it is possible to use a widget, but still the button is also available for retro fans. In addition, statistics is very important for managers. They constantly want to know whether the website and administration of it are working properly. Therefore, there is another useful function - the maintenance planning. Even the most stable sites and servers must be updated or rebooted from time to time. At the same time, it’s not the desired to lose so-called “9s” in terms of uptime. Planning of the maintenance let us achieve two goals (together or separately). This includes: not to send error notifications and not to record errors to the statistics during a specific span of time. Of course, it seems to be a kind of cheating, but outlined maintenances are justified, especially in excluded time. In addition to this, different verifications have being done and written to the log during maintenances. It can be useful for webmasters and administrators, as log let determine exactly the duration of updating or restarting processes, any occurred errors, other breakages etc. Moreover, thanks to that, the whole process of error emergence could be tracked: from the stage when the server wouldn’t be available for some time to the stage when the application would return an error.

Maintenance can be scheduled as a one-time job or on a regular basis. For example, if the backup is done every night, or a new release - every Thursday. The only condition is that the maintenance schedule should be made up at least 12 hours prior to the site/server nearest suspension period of time. This is done to ensure that all maintenances won’t be responsible for any pity unexpectancies, and statistics provided by HostTracker will be trustful.

A kind of an epilogue

We are frequently asked why are we doing that. The same things can be done without HostTracker’s help.  And you know what - definetely, they can. Especially, if you need only one tool. Many people are talking, that the whole Business World is built on human laziness. By solving routine problems, HostTracker provides a slice of work-free and responsibility-free time in the customer’s schedule. Truly, not everyone is able to assemble a car by himself. We look up to the people, who are eager to create something good for personal needs in our field, but most people don’t want to spend their free time for doing something like that.

Additionally, our clients are: non-IT specialists; IT specialists who have to report something to their managers; managers themselves; fans of reliability – they use their own tools and take advantages of someone else’s; and many other groups of people.

All in all, we are always looking forward to your comments.

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