Troubleshooting DNS

When troubleshooting DNS problems, ask yourself the following basic questions:

What application is failing? What works? What doesn't work?

does the failing application use NetBIOS names, DNS names, or hostnames?How are the things that do and don’t work related?Have the things that don’t work ever worked on this computer or network? If so, what haschanged since they last worked?Windows Server 2012 provides several useful tools, discussed in the following sections, that canhelp you answer these questions:

Is the problem basic IP connectivity, or is it name resolution? If the problem is name resolution,

Nslookup is used to perform DNS queries and to examine the contents of zone files on local and remote servers.

DNSLint is a command-line utility used for troubleshooting many common DNS issues.

Ipconfig allows you to perform the following tasks:

View DNS client settings.

Display and flush the resolver cache.
Force a dynamic update client to register its DNS records.
The DNS log file monitors certain DNS server events and logs them for your edification.

Using Nslookup
Nslookup is a standard command-line tool provided in most DNS server implementations, including
Windows Server 2012. Windows Server 2012 gives you the ability to launch nslookup from the

DNS snap-in.

Nslookup offers you the ability to perform query testing of DNS servers and to obtain detailed
responses at the command prompt. This information can be useful for diagnosing and solving name
resolution problems, for verifying that resource records are added or updated correctly in a zone, and
for debugging other server-related problems. You can do a number of useful things with nslookup:
Use it in noninteractive mode to look up a single piece of data.
Enter interactive mode, and use the debug feature.
Perform the following from within interactive mode:
Set options for your query.
Look up a name.
Look up records in a zone.
Perform zone transfers.

Exit nslookup.

Using DNSLint
Microsoft Windows Server 2012 DNS can use the DNSLint command-line utility to help diagnose
some common DNS name-resolution issues and to help diagnose potential problems of incorrect
delegation. You need to download DNSLint from the Microsoft Download Center.

DNSLint uses three main functions to verify DNS records and to generate a report in HTML:

dnslint /d This function helps diagnose the reasons for “lame delegation” and other related DNS
problems.

dnslint /ql This function helps verify a user-defined set of DNS records on multiple DNS servers.


dnslint /ad This function helps verify DNS records pertaining to Active Directory replication.

The following are some sample queries:
dnslint /d stellacon.com
dnslint /ad /s 192.168.36.201
dnslint /ql dns_server.txt
dnslint /ql autocreate
dnslint /v /d stellacon.com
dnslint /r newfile /d stellacon.com
dnslint /y /d stellacon.com

dnslint /no_open /d stellacon.com

Using DNSCmd
DNSCmd allows you to display and change the properties of DNS servers, zones, and resource records
through the use of command-line commands. The DNSCmd utility allows you to modify, create, and
delete resource records and/or zones manually, and it allows you to force replication between two DNS servers.

lists some of the DNSCmd commands and their explanations.

 DNSCmd command-line options
Command Explanation

dnscmd /clearcache Clears the DNS server cache

dnscmd /config Resets DNS server or zone configuration

dnscmd /createdirectorypartition Creates a DNS application directory partition

dnscmd /deletedirectorypartition Deletes a DNS application directory partition

dnscmd /enumrecords Shows the resource records in a zone

dnscmd /exportsettings Creates a text file of all server configuration information

dnscmd /info Displays server information

dnscmd /recordadd Adds a resource record to a zone

dnscmd /recorddelete Deletes a resource record from a zone

dnscmd /zoneadd Creates a new DNS zone

dnscmd /zonedelete Deletes a DNS zone

dnscmd /zoneexport Creates a text file of all resource records in the zone

dnscmd /zoneinfo Displays zone information


dnscmd /zonerefresh Forces replication of the master zone to the secondary zone