DNS
What is a Domain Name System?¶
According to this article, The domain name system, more commonly known as “DNS” is the networking system in place that allows us to resolve human-friendly names to unique addresses.
In short, DNS tranlates a hostname into an IP address for that host.
A-Record:¶
It is used to find the address of a computer connected to the internet from a name (domain name). In other words, The "A” record is used to map a host to an IPv4 IP address
Domain Name ---> Registrar ---> IP Address
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If DNS goes down your site can't be reached by users.
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DNS records expires
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DNS is part of the security mechanism for HTTP which includes SSL encryption and cookie privacy
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DNS record have a TTL (Time to Live) which tells the caches on how long to cache them for
The Resolver:¶
The DNS client code is built into every OS.
C-Name or FQDN:¶
It is used to specify that a domain name is an alias for another domain.
example www.github.com
is an c-name or alias for github.com
Search Domain:¶
A setting in the resolver configuration that makes the resolver look up names inside a domain
example of DNS worker in action:
A
record forwww.google.com
can be found on thename server
forwww.google.com
.NS
record forwww.google.com
resides in thecom
server which is a `gTLD (Global Top level Domain)- The
NS
for.com
are stored in the root servers