DNS Basics Flashcards
What is DNS?
DNS (Domain Name System) provides a name to number (IP address) mapping or translation, allowing internet users to use, easy to remember names and not numbers to access resources on a network and the Internet.
All devices (computers etc) that are connected to the Internet, your own network, or company network are identified by a unique number. What is that known as?
An IP Address.
Though IP Addresses are great at helping uniquely identify everything connected to the internet and/or networks, what inherent problem do they present?
IP addresses are easy for computers to process but they are not so easy for people to remember.
To make it easy for humans to remember individual computers on a network, what is used?
Host Name.
What are host files?
On early computer networks, they were simple text files that were created that mapped hostnames to IP addresses.
Why did host files become impractical?
The location for the hosts’ file is normally C\windows\system32\drivers\etc
As network sizes increased the hosts’ file approach became impractical due to the fact that:
- It needed to be stored on each computer
- The text file could take a long time to process due to the fact that it was unstructured.
- Updates were difficult to manage as all of the computers would need to be given an updated file.
How was the host file system issue overcome?
To overcome these (and other) limitations the DNS system was developed.
What does the DNS system provide for?
- A way to organize the names- Domain name structure
- Protocols ,services and methods for storing,updating, and retrieving IP addresses for hosts computers.- DNS System
From the perspective of the end-user, what can a DNS system be considered as?
A structured hosts file.
How can a hosts file be defined?
The hosts file is simply a list of names and IP addresses with no structure making it difficult to scale to a large number of machines.
How was the non-existent structure of hosts file resolved?
Domain Name Structure was the solution which was to place the machines into administrative areas known as domains and arrange the domains in a hierarchy.
This takes the form of a tree-like structure that resembles the file system structure found on computers.
What is the DNS System?
The DNS system consists of many Domain Name servers that together provide the name to IP address mapping for registered devices (usually servers) on the Internet.
The main DNS severs (root servers) are owned and managed by a variety of different organizations, and are located mainly in the USA.
Here is a list http://www.iana.org/domains/root/servers.
Other companies including ISPs have their own DNS servers which are linked to the root servers in a hierarchical fashion providing a distributed system.
Fortunately you don’t need to manage a DNS server or create DNS records to use the Internet.
However you need to have access to a DNS server.
How would you access a DNS server?
To access a DNS server you will need the IP address of the DNS server.
This is usually supplied to you by your ISP (Internet Service Provider).
Most client computers/devices will be configured to obtain an IP and a DNS server address automatically. (see below)
How can you use the Command Line Interface (CLI) to access your devices assigned IP and DNS Address?
ipconfig/all
If your DNS isn’t working properly you can’t access other machines on the internet using their name.
Is there any other way your machine can access other machines on the internet?
Yes. You would use their IP Address.