NI_HOST_TO_ADDR failed (resolve the hostname)

Dependent on the problem cause (and operating system specific).

1. Network configuration is not correct
------------------------------------------------------------------------------------------------------------------------------------------------
What can be done?
- Check whether the name that could not be resolved according to the error message can be resolved with simple operating system commands:

* ping <hostname>            (simple operating system test)

  if the same error occurs here, the configuration is incorrect
  -> Check the resolution sequence (operating-system-dependent!!)
      In which sequence are the hosts file, DNS and NIS evaluated?
        HP UX 10.0 /etc/nsswitch.conf
              (Default order: /usr/newconfig/etc/nsswitch.conf)
        AIX 4.1    /etc/netsvc.conf

  Depending on the resolution sequence and the required   configuration (whether DNS used or not), check the configuration   (operating-system-dependent!)
    -> If the affected name is correct in the hosts file (check upper        and lower case)
    -> DNS: Server entered correctly in /etc/resolv.conf?
            Does the DNS server know the name in the correct             syntax (check this with nslookup)?

- Check whether the resolution works with standard calls:

* saphostbyname <hostname>
   (an SAP program that checks the resolution of names)
   If ping works and saphostbyname does not, version problems are    very likely (see point 2).

2. Version problems
------------------------------------------------------------------------------------------------------------------------------------------------
If the tests described in point 1 do not report any problems, there may also be version problems. These problems result from HP (HP UX 9.0 -> HP UX 10.0) and IBM (AIX 3.2.5 -> AIX 4.1) changing the procedure for name resolution in the new operating system release.
The problem occurs, as programs in different SAP R/3 Releases were translated with older operating system releases. If these programs are executed on a new operating system release, they cannot use the new resolution mechanism (the linked operating system libraries still use the old mechanism).

These problems only occur if either DNS or the hosts file were not maintained correctly. With the new mechanism, a "higher-level" file (HP: /etc/nsswitch.conf) (AIX: /etc/netsvc.conf) determines the resolution sequence.
Example:
   The config file (HP: /etc/nsswitch.conf) (AIX: /etc/netsvc.conf)    determines that only the local hosts file should be used, the file    /etc/resolv.conv (shows the DNS is active in older OS releases),    however, is still there.
   Result: - the new program (and thus also the OSS) work across              the local hosts file -> OK
             - the old program does not recognize the new config               files and finds /etc/resolv.conf. The linked libraries               thus attempt name resolution via DNS. If DNS still does               not work correctly, the program reports an error.
Solution:

- Correct the configuration (depending on the operating system and   strategy)
  - if DNS is not required, delete or rename /etc/resolv.conf.

- If a quick correction is not possible:
  => Switch to a local hosts file (to continue R/3 operation or      the upgrade)
     - Maintain hosts file correctly (addresses of the required        servers)
     - Delete/Rename /etc/resolv.conf
     - Change (HP: /etc/nsswitch.conf) (AIX: /etc/netsvc.conf) so        that only the local hosts file is evaluated.
       HP:
          Contents of /etc/nsswitch.conf :
            formerly:" DNS files NIS "   ->  Now " files "
       AIX:
       Contents of /etc/netsvc.conf
       formerly: "hosts = bind,local"   -> now "hosts =local"
       (bind stands for Berkely internet name deamon - DNS)