What Is a DNS Server?
A DNS server is a computer server that contains a database
of public IP addresses and their associated hostnames, and in most cases serves
to resolve, or translate, those names to IP addresses as requested. DNS servers
run special software and communicate with each other using special protocols.
The Purpose of DNS
Servers
It's easier to remember a domain or hostname like tezhost.com
than it is to remember the site's IP address numbers 123.456.789.123.
When you access the Life wire website, all you must type is
the URL https://www.tezhost.com. Conversely, computers and network devices
don't work well with names when trying to locate each other on the internet.
It's far more efficient and precise to use an IP address.
Malware Attacks That
Change DNS Server Settings
Always run an antivirus program because malware can attack
your computer in a way that changes the DNS server settings.
For example, if your computer uses Google's DNS servers
(8.8.8.8 and 8.8.4.4) and you open your bank's website, you naturally expect
that when you enter its familiar URL, you'll be sent to the bank's website.
However, if malware changes your DNS server settings, which
can happen without your knowledge after an attack on your system, your system
no longer contacts Google's DNS servers but instead a hacker's server that
poses as your bank's website. This fake bank site might look exactly like the
real one, but rather than logging you into your bank account, it harvests the
username and password you just typed, giving the hackers the essential
information, they need to get into your bank account.
Malware attacks that hijack your DNS server settings may
also redirect traffic away from popular websites to ones that are full of
advertisements or to a fake site designed to scare you into believing your
computer has been infected with a virus, and that you must buy their advertised
software program to remove it.
Protecting Yourself from
DNS Attacks
There are two things you should do to avoid becoming a
victim of a DNS settings attack. The first is to install antivirus software so
that malicious programs are caught before they can do any damage.
The second is to pay close attention to the appearance of
important websites you visit regularly. If you visit one and the site looks off
in some way—maybe the images are all different or the site's colors have
changed, or menus don't look right, or you find misspellings (hackers can be
dreadful spellers)—or you get an "invalid certificate" message in
your browser, it might be a sign that you're on a faked website.
How DNS Redirection
Can Be Positively Used
This ability to redirect traffic can be used for positive
purposes. For example, OpenDNS can redirect traffic to adult websites, gambling
websites, social media websites, or other sites network administrators or
organizations don't want their users visiting. Instead, they may be sent to a
page with a "Blocked" message.
Primary and Secondary
DNS Servers
In most cases, a primary and a secondary DNS server are
configured on your router or computer when you connect to your internet service
provider. There are two DNS servers in case one of them happens to fail, in
which case the second is used to resolve hostnames you enter.
Why You Might Change
Your DNS Server Settings
Some DNS servers can provide faster access times than
others. This is often a function of how close you are to those servers. If your
ISP's DNS servers are closer to you
than Google's, for example, you may find domain names are resolved quicker
using the default servers from your ISP than with an external server.
If you experience connection problems where it seems no
websites will load, it's possible there's an error with the DNS server. If the DNS server can’t find the correct IP address
that's associated with the hostname you enter, the website can't be located and
loaded.
DNS Root Servers
There are 13 important DNS root servers on the internet that
store a complete database of domain names and their associated public IP
addresses. These top-tier DNS servers are named A through M for the first 13
letters of the alphabet. Ten of these servers are in the US, one in London, one
in Stockholm, and one in Japan.
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