DNS.GetHostEntry doesn't display the hostname as dns.resolve did

DNS.GetHostEntry doesn't display the hostname as dns.resolve did

• Upul-uj

  I sent an email to Durgaprasad Gorti above (apparently M$) but no response.
  

• gsl3

  I am having the same issues as you except that it throws an error for me.

  We could really use a response MS

  I am going back to Resolve for the time being.

  
  

• eaho

  Does the IP address you are trying to resolve have a PTR record in your DNS Server If not, I don't think it will do a reverse lookup

  To find out perform the following from the command line (Assumes the IP address you are trying to lookup is 192.168.1.1).

  nslookup

  set type=ptr

  1.1.168.1.in-addr.arpa

  I'll bet you don't get a hostname back. BTW, notice that the 3rd line is the ip address with it's octets reversed and the .in-addr.arpa attached.

  I'm not totally sure, but I think that .Resolve may have used a NetBios query if the DNS reverse lookup failed..

  
  

• Miechu

  Hi,

  I have same kind of problem. Actually my development station have 2 networks cards, on two subnets (10.10.0.1 & 10.162.130.1). I want to convert my code to use the newer GetHostEntry, but if I try by using the IP address, GetHostEntry can't found my machine name. For test purpose I try this code:

  Dim test1, test2, test3, test4, test5 As String
  test1 = Dns.Resolve("10.10.0.1").HostName
  test2 = Dns.GetHostEntry("10.10.0.1").HostName
  test3 = Dns.Resolve("10.162.130.1").HostName
  test4 = Dns.GetHostEntry("10.162.130.1").HostName
  test5 = Dns.GetHostEntry(IPAddress.Parse("10.162.130.1")).HostName

  The station is alone on the 10.10.0.1 network, and the DNS Server is on the other network. The first two tests, return my own address (10.10.0.1), it seam good because the DNS don't any reference to this address. The problem come when I try with the other address. The Resolve return my station longname , but the two last GetHostEntry report an error, like "Unknow Host".

  Is anything wrong with this method to get the host name

  Thank
  Jacques

  
  

• lympanda

  Did anyone find the reason to why .GetHostEntry doesn't work as good as .Resolve does

  What is the technical difference between .GetHostEntry and .Resolve anyway Is there any way to work around this problem
  
  Thanks.

  
  

• Mikhail Kurskiy

  I am having the same problem with GetHostEntry, it's broken. I am forced to use Resolve, which is marked obsolete. I can't believe you're not going to fix it for XP.

  Feedback: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx FeedbackID=97815

  
  
  

• Mahesh Hegde

  The issue is the reverse lookup. Traditionally DNS Servers are supposed to resolve the names to addresses. The reverse of that - looking up a host name based on IPAddress is not reliable and in Ipv6 it is not supported. So my recommendation is to not to write apps that rely on reverse lookup.

  I will look into why exactly the difference exists in GetHostEntry and Resolve.

  
  
  

• Vlad Pitaru

  As noted above, the following is probably your answer:

  IPHostEntry e = Dns.GetHostEntry(IPAddress.Parse("x.x.x.x"));

  Console.WriteLine(e.HostName);

  
  
  

• Brian McDonald

  I want to thank Microsoft for ruining a perfectly operable code such as Dns.Resolve(stringIp).

  I tried the above code, although it does work, It's not the aggessive code that .Resove was.

  Is there still any imaginable way to use Dns.Resolve. It still appears in the Intellisence dropdown menu, so it must apply somewhere.

  
  

• LionelG

  Agreed, using obsolete code is bad practice and there appears to not be any other option for the mean time. I don't understand why microsoft would release updated code with reduced functionality i.e. the removal of the reverse lookup function

  How frustrating.

  
  

• Neel13

  Did you check the value of IPHostEntry.HostName

  Can you put the code, where you do dns query

  
  

• ddas

  Before you thank us profoundly, could you please tell us
  what it is that you are missing in Resolve that is not there in
  GetIPHostEntry
  
  

• Bob Lee

  I am having an issue with this. The problem is easily demonstrated in the debug window:

  This returns a computer name:

  System.Net.Dns.GetHostByAddress("192.168.1.9").HostName.ToString

  This returns a computer name:

  System.Net.Dns.Resolve("192.168.1.9").HostName.ToString

  But this returns an IP address

  System.Net.Dns.GetHostEntry("192.168.1.9").HostName

  But the compiler doesnt let you use Resolve or GetHostByAddress any more. Would appreciate any feedback on how to get the hostname without using the debug window

  thanks

  
  

• Twil1ght

  BTW the workaround is to turn "treat all warnings as errors" off in project properties, and then the compiler lets you use the old functions, but thats absolute rubbish of course for anyone who want to write good code!
  
• DNS.GetHostEntry doesn't display the hostname as dns.resolve did