IP, DNS, confussion

Why do I get a different ip address showing on different network scanner apps? I’ve looked up the addresses in Whois and all I’m getting back is this is a private address. I don’t understand how they differ from apps.

Now DNS this just goes straight over my head. I just don’t get it. 172.30.139.16 always makes an appearance but all I get is this is a private address? What am I missing here? Also my loopback address had made an apperance how is that possible?

If you are using a nat router you get a IP normally in the range 192.68.1.1 that is issued by the router depending on setting on the router it will change every X mins none of these IPS can be seen on the internet only the live IP of the router is seen. The DNS by default will be very slow router you should set it to the fast 1.1.1.1 & 1.0.0.1 DNS converts the name of a site into a IP so it can connect

WindowPane10 said:

...172.30.139.16 always makes an appearance but all I get is this is a private address...

An IP address is used to connect to a machine wherever it is on the web. If every machine in the world had to have a unique IP address then there wouldn't be enough to go round. So a number of private address ranges are reserved for use only on a network that is not directly connected to the web. These Private address ranges include 192.168.0.0 - 192.168.255.255 and 172.16.0.0 - 172.31.255.255. These are free for anyone to use on their own private networks because they are never used on the web.

Such a network would be your home network, or a corporate business network. To access the web IP traffic goes through a router which has an outward facing unique IP address to connect to the web, and an internal facing IP address from a private address range to connect to the PCs on your network. Most domestic routers use the 192.168.xxx.xxx private address range.

Windows can use private address ranges for its own purposes. I use Hyper-V virtual machines on one of my PCs, that will use the 172.16.xxx.xxx IP address range for internal communications, for example.

In order to route traffic on the Internet, you need a valid routable outside IP address. You can find out what your ISP's provided valid IP address is by hitting something like, What Is My IP Address - See Your Public Address - IPv4 & IPv6.

However, once you install a router on your network, you use private IP addresses behind the router that are not routable directly on the network. These addresses are defined by RFC 1918. (10.0.0.0/8, 172.16.0.0/12 192.168.0.0/16).

So, let's say that your PC is behind a router, and the PC's internal IP address is 192.168.1.100. You want to go to www.pepsi.com. Well, your computer will do a DNS lookup to see what the IP address of www.pepsi.com is (45.60.75.51). Since that IP is not on your local 192.168.1.0 network, it will go to your default gateway (192.168.1.1...your router), from there, your router will do NAT (network address translation) and will say "hey, 192.168.1.100 wants data from 45.60.75.51, therefore, I will put the ISP's legit address of 19.22.31.4 and send the data to 45.60.75.51 and I will make an entry saying when data comes back from 45.60.75.51, I should give that to 192.168.1.100. So, when the data comes back, the router sees that a client (192.168.1.100) requested it, it takes off the valid routable address of 19.22.31.4, and puts 192.168.1.100 and delivers the data to your PC.

DNS is responsible for translating a friendly name (www.pepsi.com) to an IP address (45.60.75.51). Your ISP provides DNS servers which can answer these queries for you, or you can use public DNS servers such as 8.8.8.8 or 4.4.2.1. So, your router typically becomes the host on your network that you send your DNS queries to and it knows to translate your requests to your ISP's DNS server, or one of the public DNS servers if you have set them up.