Some simple command line utilities you can use on your Windows and Linux computer to test DNS resolution. this will also show you how you can quickly test if you have resolution via a name server or not. Many times this comes up, a DNS server is down; client loses IP connectivity and can”t resolve DNS, DNS cache poisoning. Using this handy tools can guide you quickly to see how you can test to see if your system is ”ok” and resolving names to IPs properly.

1. You have to see if DNS resolution is working you can see if the DNS server you are configured to query.

C:\Documents and Settings\raxso>nslookup www.google.com
Server: everest.local
Address: 192.168.1.200

Non-authoritative answer:
Name: www.l.google.com
Addresses: 72.14.235.99, 72.14.235.147, 72.14.235.104
Aliases: www.google.com

2. When you query my Local DNS I can see that www.google.com has mulitiple IP addresses.

3. Now, you can ping with the -a switch to also verify if DNS resolution is work. Pinging Google’s IP address with the -a switch produces the DNS name of the system.

C:\Documents and Settings\raxso>ping -a 72.14.235.99

Pinging tw-in-f99.google.com [72.14.235.99] with 32 bytes of data:

Reply from 72.14.235.99: bytes=32 time=85ms TTL=245
Reply from 72.14.235.99: bytes=32 time=85ms TTL=245
Reply from 72.14.235.99: bytes=32 time=85ms TTL=245
Reply from 72.14.235.99: bytes=32 time=97ms TTL=245

Ping statistics for 72.14.235.99:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 85ms, Maximum = 97ms, Average = 88ms

Although this is a simple command line but very helpful when you are troubleshooting network connectivity and DNS resolution.