Understanding the Basics of DNS and IPs
What is 'DNS'?
DNS stands for 'domain name system'. Specifically, DNS is the protocol that allows you to type 'http://hubpages.com/' and see the correct web site.
All computers on the internet are identified to the network using an IP (Internet Protocol) number. In the old IP4 system, this number will look something like this: 22.214.171.124 (this is the IP for Hubpages). These numbers are not very human readable and certainly not easy to remember. IP6, a new protocol designed to allow more 'space' in terms of internet addresses is even worse.
Therefore, each computer also has a name, such as 'hubpages.com'. In some cases, the name may refer to a collection of computers. Major sites such as Amazon or Google may have hundreds of servers all answering to the same name.
However, computers don't know they have names. Computers, at the basic level, only do numbers. When you type the name into the URL bar, the DNS server translates it into a number.
Where is the DNS Server?
The term DNS server dates back to the early days of the internet, when an ISP, or a company, or a college, would have a dedicated computer that did nothing but resolve domain names.
These days, people's televisions have more computing power than some of those old mainframes. 'DNS server' has become something of a legacy term. Dedicated DNS servers still exist, but you are most likely not using one. Instead, your DNS server is actually a piece of software. This software might be running on your computer or on a computer at your ISP. If you connect to the internet through a router or cable modem, then the DNS server software most likely runs on your router. DNS software that is on your computer or home router is called a 'local DNS'. If it's at your ISP, it's a 'remote DNS'. You might also be using a 'public DNS' (Google has one). However, most people who are not tech savvy use whatever their computer sets up as a default. This is most often, these days, a local DNS.
When DNS goes wrong
DNS failure is a lot less common than it used to be. Those of us who remember the internet in the 1990s will remember that DNS servers were the subject of curses across the globe. They were notoriously unreliable.
These days, your DNS server probably works 99% of the time. Many casual computer users don't even know it exists. When it does fail, though, then bad things happen.
DNS failure will give an error in your web browser. In Firefox, you will get 'Firefox can't find the server at <address>'. In Chrome, the error is 'This web page is not available'. In IE, you will get 'The page cannot be displayed'.
Any other internet programs will fail with a similar message, including sending email and using FTP.
The first thing to do when you get a DNS resolution failure is to try and load a different site. Pick one you haven't been to that day (or you might get a cached page).
If you can load most sites, then the problem is the DNS server on the site you're trying to load. There's not much you can do about this, other than try and contact the site's owner if possible. If it's your web site, you will need to talk to your hosting provider.
If you can't load anything, then it is your DNS that is not working.
Nine times out of ten, however, this is an easy fix. The fix is to restart the DNS software. This means you will need to reboot both your computer and your moden or router. If you are using a local DNS, this will normally fix it. Repeated DNS failures may mean that your router is starting to wear out and it's time to think about getting a new one.
If the DNS is supplied by your ISP, you will have to call them. To find this out, you will need to go to your computer's network preferences.
On a Mac, go to System Preferences and open Network. On a Windows PC, this is a little harder - you will need to go to Start ---> All Programs ---> Accessories ---> Command Prompt and then type ipconfig /all.
Look at the IP given next to 'DNS Server'. On the Mac, if this is the same as 'Router', then your router is running your DNS software. On the PC, look for the DNS server to be the same as your IP with the last number different. Most likely, it will be lower.
If the IP is completely different, then your ISP is running your DNS server and you will need to call them and report the problem.
Using a Public DNS Server
If you have a lot of DNS problems, then you might want to change to a public DNS server. You can generally get a list of these by typing 'public DNS server' into Google. One good option is to use Google's public DNS server, which has the IP 126.96.36.199.
On a PC:
Control Panel -> Network and Internet -> Network and Sharing Center -> Change adapter settings.
You will either need to right click Local Area Connection, if using a wired connection, or Wireless Network Connection if wireless, then select Properties.
Select the Networking tab. Then select Internet Protocol (it will say either Version 4 or Version 6) and click properties.
Then go to Advanced > DNS
Write down your DNS server address. Then remove them and click OK.
Go to 'Use the following DNS server addresses'. Write down any IP addresses that show under Preferred DNS server or Alternate DNS server.
Then replace Preferred with 188.8.131.52 (or 2001:4860:4860:8888 if you have a newer computer that uses IPv6). You might also replace Alternate with 184.108.40.206. Or you can replace alternate with your ISP's server or the reverse.
Close network preferences and make sure everything still works.
On a Mac:
Go to System Preferences -> Network
Select either Ethernet or Wi-Fi.
Click on Advanced.
Select the DNS tab.
Click on the + button at the bottom under DNS Servers.
Type in 220.127.116.11. You can then re-add your router's DNS as an alternate.
For most people using a local DNS is faster, but if you have an iffy router, using a public DNS can help. This can also help get around problems with a specific site or sites.
Finding out an IP
For most people, the IP of a site is useless information. However, the IP can be used to connect to a site even if the DNS server is down (most of the time - in some cases, if there are major problems, this won't work, and some web servers block direct IP connections). Site administrators often use IPs to track specific users (any device connected to the internet has to have an IP, but does not necessarily have to have a name).
Your DNS server translates the name into the IP and back, so it would make sense for it to be able to get the IP for you.
If you need the IP, you can get it in the following ways:
On a PC, do the following:
Start > All Programs > Accessories > Command Prompt
Then type 'nslookup <domain>', for example 'nslookup hubpages'.
There are also utilities you can download that will do this from within Windows.
Macs come with a utility to do this pre-installed. You'll find it in Applications > Utilities, and it's called 'Network Utility'. Open this application and select the 'Lookup' tab, then just enter the address in the field. Alternatively, you can open Terminal and type 'nslookup <domain>'.
There are two other useful utilities that relate to DNS and IPs.
ping <host name> will tell you what the network lag is like to a specific site.
traceroute or tracrt <host name> is even more fun. This will show you exactly what routers your data has to go through to get to and from the other site.
Neither of these are things the average user needs, but if you want to understand more about internet networking, traceroute can be rather cool to play with.