Source:How to check DNS configuration: Difference between revisions

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=== Windows Systems ===
=== Tools to check DNS Resolution ===
 
There are various tools which can be used to check the DNS resolution, they have up and downsides.
 
==== nslookup (windows and linux) ====
 
This tool can be used to query and existing DNS Server for a certain hostname or ip address. It
will NOT check the hosts file of the System. As such, you may get different results if you choose
to use nslookup. Sesam resolves its hostnames via common library function and will first use
the hostname specified in the hostsfile of the system.
 
==== host (linux only) ====
 
As nslookup, host can be used to forward and reverse resolve hostnames and ip adresses. It
defaults to the DNS server configured in /etc/resolv.conf but can also be used wit a certain
DNS Server as additional argument. It will query the DNS Server of the System first.
 
==== sm_setup check_resolution (recommended) ====
 
This is the recommended way to check your DNS Resolution. Both client and backup servers
come with the sesam tool "sm_setup" installed. It can be used to forward and reverse resolve
DNS names from the Command Line

Revision as of 13:40, 13 July 2011

How to check DNS configuration

General

Most of our customers face problems while configuring new clients. Often the source of the problems are misconfigured DNS Servers, or no functional DNS at all. This document describes how to use Sesam with DNS names and how to check wether if you DNS configuration is OK.

Requirements and Rules

  • Sesam needs a propper DNS names to work, it will NOT work with IP Adresses
  • All DNS Names have to correctly resolve forward and reverse
  • If no DNS Server is available, the hosts file of the client and backup server have to be used for make systems available via DNS name

Configuration

Common Error Messages

There are some common error messages which are an indication for errors in your name resolution:

CLIENT_HOSTNAME: Login to stpd from <CLIENT_HOSTNAME> to <SESAM_SERVER_HOSTNAME> incorrect.
Login incorrect. Client resolves his IP address [X.X.X.X] to [RANDOM_HOSTNAME], but server resolves it to [X.X.X.X]. Please adjust your name resolution.  (0)


Tools to check DNS Resolution

There are various tools which can be used to check the DNS resolution, they have up and downsides.

nslookup (windows and linux)

This tool can be used to query and existing DNS Server for a certain hostname or ip address. It will NOT check the hosts file of the System. As such, you may get different results if you choose to use nslookup. Sesam resolves its hostnames via common library function and will first use the hostname specified in the hostsfile of the system.

host (linux only)

As nslookup, host can be used to forward and reverse resolve hostnames and ip adresses. It defaults to the DNS server configured in /etc/resolv.conf but can also be used wit a certain DNS Server as additional argument. It will query the DNS Server of the System first.

sm_setup check_resolution (recommended)

This is the recommended way to check your DNS Resolution. Both client and backup servers come with the sesam tool "sm_setup" installed. It can be used to forward and reverse resolve DNS names from the Command Line