1) check for spelling mistakes

2) next for domains : .org, .gov etc

3) check for https://www.yahoo.com

4) check for incorrect entries like - w.yahoo.co.in

5) check for the ip adress of yahoo and paste it on ur 
broswer and check

6) change Ip adress and check

the negative test cases for www.yahoo.com is "page can not 
be displayed"

-Try enetring invalid extensions like ww.yahoo.edu,Yahoo.org
-Trying to login with invalid username and password.

1.enter the yahoo address with iavalid URL 
www.ya.hoo.vom, w.yahoo.com
2.enter the yahoo address with spaces www.ya ha o.com
3.enter the yahoo address with numbers www.ya123hoo.com
4.enter the yahoo add with special characters 
www.ya@#hoo.com
5.enter the yahoo add with blank www.      .com

1.Open IE.The blank page of IE is not opened due to 
improper connections,network problems etc.
2.Enter invalid URL of Yahoo page in the address bar.
eg:www.yahoocom
   ww.yahoo.co
   wwwyahoocom
3.Enter blank address bar and check for the functionality.
4.Enter special characters or numbers or spelling mistakes 
in the address box and check for the warning message"Page 
cnnot be displayed/server error/etc"
5.Check whether this URL is able to open in google account.