Is there a way to figure out the country name just by looking at an IP address? I mean, do countries have specific ranges of IP addresses? For example, Australia can have IP addresses only in the range of 123.45.56.89 - 231.54.65.98
(just an example)
No you can't - IP addresses get reallocated and reassigned from time to time, so the mapping of IP to location will also change over time.
If you want to find out the location that an IP address currently maps to you can either download a geolocation database, such as GeoLite from MaxMind, or use an API like http://ipinfo.io (my own service) which will also give you additional details:
$ curl ipinfo.io/8.8.8.8
{
"ip": "8.8.8.8",
"hostname": "google-public-dns-a.google.com",
"loc": "37.385999999999996,-122.0838",
"org": "AS15169 Google Inc.",
"city": "Mountain View",
"region": "California",
"country": "US",
"phone": 650
}