Recently, I faced power Failure in my Data Center and face an Active Directory / DNS Crash as well. I setup Active Directory and DNS to support my users and organization but start dns errors after a day. Active Directory starts replication but after DNS Server response Default Server Unknown on nslookup. Ooops ! I was really worried that what happens to it dns server but obviously, I start troubleshooting on it. I tried and found the solution but it was much unexpected to me.
DNS Server Solution 1:
DNS Server response Default Server Unknown can be faced if your DNS Server haven’t setup with reverse lookup zone. If it’s already done than you need to create a PTR Record and point to 192.168.10.10 Server (in my example). After creating PTR Record or configuring Reverse lookup zone, you will be able to see Server Name, as image below.
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DNS Server response Default Server Unknown Solution 2:
In some cases, your DNS may behave differently like it shows exact Default Server Name but on giving any website name (google.com), it show error message like “request timed out. timeout was 2 seconds” etc. in this case you have to check your Firewall on DNS Server or any Firewall between your computer and DNS Server and you have to allow your DNS Server.
DNS Server response Default Server Unknown Solution 3:
You may notice that even disabling Firewall on DNS Server, Local Computer or even allowing DNS Server in middle Firewall doesn’t help then you must check that your DNS Server have properly configured for Live DNS Server’s. Please double check Live DNS IP Address in DNS Forwarders and hope these tips will help you, please show yourself in comments to improve the post.
