Resolve host name to an ip address

Question

I developed a client server simulation application  I deployed client and server on two different Windows XP machines  Somehow  the client is not able to send requests to the server   I tried below options    Pinged server machine successfully from client using ip-address  Pinged client machine successfully  from server using ip-address  Checked netstat command line tool from both machines  Server is in LISTENING mode and client is in SYS SENT mode  But the foreign address it is using to send is host name not the ip address  Pinged server machine unsuccessfully using host name from client  Pinged client machine successfully using host name from server    I feel the problem is when the client is trying to connect to the server using the host name   Could you please let me know how to force an application to use an ip address instead of a host name  Is there any other way to map the host name to an ip address

User · Answer

This is hard to answer without more detail about the network architecture  Some things to investigate are    Is it possible that client and or server is behind a NAT device  a firewall  or similar  Is any of the IP addresses involved a  local  address  like 192 168 x y or 10 x y z  What are the host names  are they  real  DNS able names or something more local and or Windows-specific  How does the client look up the server  There must be a place in code or config data that holds the host name  simply try using the IP there instead if you want to avoid the lookup

User · Answer

Go to your client machine and type in   nslookup server company com   substituting the real host name of your server for server company com  of course   That should tell you which DNS server your client is using  if any  and what it thinks the problem is with the name   To force an application to use an IP address  generally you just configure it to use the IP address instead of a host name  If the host name is hard-coded  or the application insists on using a host name in preference to an IP address  as one of your other comments seems to indicate   then you re probably out of luck there   However  you can change the way that most machine resolve the host names  such as with  etc resolv conf and  etc hosts on UNIXy systems and a local hosts file on Windows-y systems

User · Answer

Try tracert to resolve the hostname  IE you have Ip address 8 8 8 8 so you would use  tracert 8 8 8 8

User · Answer

Windows XP has the Windows Firewall which can interfere with network traffic if not configured properly   You can turn off the Windows Firewall  if you have administrator privileges  by accessing the Windows Firewall applet through the Control Panel   If your application works with the Windows Firewall turned off then the problem is probably due to the settings of the firewall   We have an application which runs on multiple PCs communicating using UDP IP and we have been doing experiments so that the application can run on a PC with a user who does not have administrator privileges   In order for our application to communicate between multiple PCs we have had to use an administrator account to modify the Windows Firewall settings   In our application  one PC is designated as the server and the others are clients in a server client group and there may be several groups on the same subnet   The first change was to use the functionality of the Exceptions tab of the Windows Firewall applet to create an exception for the port that we use for communication   We are using host name lookup so that the clients can locate their assigned server by using the computer name which is composed of a mnemonic prefix with a dash followed by an assigned terminal number  for instance SERVER100-1    This allows several servers with their assigned clients to coexist on the same subnet   The client uses its prefix to generate the computer name for the assigned server and to then use host name lookup to discover the IP address of the assigned server   What we found is that the host name lookup using the computer name  assigned through the Computer Name tab of the System Properties dialog  would not work unless the server PC s Windows Firewall had the File and Printer Sharing Service port enabled   So we had to make two changes   1  setup an exception for the port we used for communication and  2  enable File and Printer Service in the Exceptions tab to allow for the host name lookup      EDIT     You may also find this Microsoft Knowledge Base article on helpful on Windows XP networking   And see this article on NETBIOS name resolution in Windows

User · Answer

You could use a C function getaddrinfo   to get the numerical address - both ipv4 and ipv6   See the example code here

[windows] Resolve host name to an ip address

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