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How to test the status of the ISP DNS

In a case you have some issues to access certain web sites or sending emails, you may want to check the status of the DNS.

Assuming you setup an internal DNS and assign the ISP DNS IP addresses in DNS Forwarders, you can use nslookup to test the DNS status.

For example, type nslookup command and press Enter, it will display the default server like below. If you receive errors, check this troubleshooting DNS page.

C:\> nslookup

Default server: chicagotech.net

Address: 192.168.5.2

To test the status of the ISP DNS, force nslookup to use the ISP DNS. To do so, type server DNS IP address following the nslookup command, for example,

> server 216.165.129.159
Default Server:  h216-165-129-159.216-165.unk.tds.net
Address:  216.165.129.159

> yahoo.com
Server:  h216-165-129-159.216-165.unk.tds.net
Address:  216.165.129.159

DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to h216-165-129-159.216-165.unk.tds.net timed-out
> yahoo.com
Server:  h216-165-129-159.216-165.unk.tds.net
Address:  216.165.129.159

DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to h216-165-129-159.216-165.unk.tds.net timed-out
> set v
> set vc
> yahoo.com
Server:  h216-165-129-159.216-165.unk.tds.net
Address:  216.165.129.159

*** h216-165-129-159.216-165.unk.tds.net can't find yahoo.com: Unspecified error

Then you will know if the ISP DNS has an issue or not. If you do see some errors or time out, contact the ISP for the resolution.

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