What is a DNS server, the possible cause of the collapse of WhatsApp, Facebook and Instagram | Domain name system

Once the global upheaval has been overcome, with the start of Facebook, Instagram and WhatsApp after a six-hour blackout, the question arises of what caused the interruption of service. While Mark Zuckerberg’s company has yet to officially report the cause of the failure, Cyber ​​security experts have indicated that this is linked to an issue with the DNS.

Domain name systems (DNS), which translate commercial domain names (Facebook, WhatsApp, etc.) into binary identifiers, or IP addresses, they would have ceased to function and that caused the downfall of the world.

This problem, however, can answer a deeper problem, which would be the release of Facebook and its products from the BGP routing system (Border Gateway Protocol). These systems allow information to flow between the various “subnets” (ISPs) that make up the Internet.

In order to clarify it, the specialists recalled, by way of example, that if the DNS is the telephone directory, the BGP is the Internet postal system. It is a protocol by which the routers of the service providers know how to send network packets, which are essentially the information that we exchange with our chat services or our social networks.

Next, Facebook’s exit from the BGP advertising system would have made the social network’s own DNS servers inaccessible to the rest of the internet, with the consequent fall of all its services.

How DNS Works

The best-known function of DNS is to allow each internet address to have a “word” associated with it, instead of a set of numbers. For example, by typing “Facebook.com”, the DNS server searches its database for the IP address with which this name is associated, and guides the browser to it, which will download the corresponding page.

For this reason, each domain name is unique and consists of a series of elements that categorize and locate it on the network.

Basically, the Domain Name System is equivalent to a web page phone book because it is a technology that establishes the IP address that should be used when people try to access specific web pages.

Each time a user registers a domain, a “WHOIS” entry is created (un protocol type) in the corresponding record and this is stored in DNS as a “resource record”.

When the address of a web page (URL) is entered in the search field of the browser, the latter makes a request to the so-called resolver, a particular component of the operating system, whose function is to put in hides the IP addresses already requested previously, and provide them when the client application (browser, mail program) requests it.

If the requested IP address is not in the resolver cache, it redirects the request to the corresponding DNS server, which, in general, is the DNS server of the Internet service provider. Here the request is checked against the DNS database and, if available, the corresponding IP address is sent in response (direct search).

This allows the user’s browser to access the desired web server on the Internet. Another solution is to go the other way around, i.e. translate the IP address into a domain address (reverse lookup).

A very common error is when “The DNS server is not responding”, and this happens when there are connection problems. This happens when the internet connection is not working and it is not possible to access a web page.