In the event you experience DNS resolution issues, please follow the below steps in the order provided and collect as much information as possible. Providing less than all outputs requested may prolong our investigation.
You will need to run the below command line prompts from an affected device and/or monitoring server.
IMPORTANT
While 3rd party tools may be favorable for DNS monitoring, we have found these types of tools do not capture the raw data our team requires to troubleshoot.
While screenshots of errors you see on the screen will help, screenshots of monitoring images are less useful due to how the data is presented. Our team requires the raw data being sent/received in logs, which is why the command line prompts are required.
Where possible, outputs should be in a readable, easily accessible format (ex: .txt) so our team can quickly review and fix. Less readable outputs (ex: screenshots, JSON) may also prolong our investigation.
Pre-Requisites
- Replace yoursitehere.com with the actual hostname/domain you're experiencing DNS issues with
- Do not use or include the full URL (http://) has to be omitted
- Replace <INSERT YOURSITEHERE.COM NAMESERVER HERE> with the authoritative Nameserver of the hostname/domain you're experiencing DNS issues with
- Can be found doing a WHOIS (https://www.whois.com/)
- Enter the hostname/domain in the Enter Domain or IP field at the top right
- Press the WHOIS button
Step 1: Use DIG or NSLOOKUP
Dig (Preferred)
dig yoursitehere.com
dig yoursitehere.com @<INSERT YOURSITEHERE.COM NAMESERVER HERE>
dig whoami.ultradns.net @<INSERT YOURSITEHERE.COM NAMESERVER HERE>
dig whoami.ultradns.net
dig whoareyou.ultradns.net @<INSERT YOURSITEHERE.COM NAMESERVER HERE>
OR
Nslookup (available via Windows command prompt typing CMD):
nslookup yoursitehere.com.
nslookup yoursitehere.com. <INSERT YOURSITEHERE.COM NAMESERVER HERE>
nslookup whoami.ultradns.net. <INSERT YOURSITEHERE.COM NAMESERVER HERE>
nslookup whoami.ultradns.net.
nslookup whoareyou.ultradns.net. <INSERT YOURSITEHERE.COM NAMESERVER HERE>
Step 2: Tracert or Traceroute
Use Traceroute on Mac and Linux systems, and tracert on Windows systems.
traceroute <INSERT YOURSITEHERE.COM NAMESERVER HERE>
traceroute crs.ultradns.net
tracert <INSERT YOURSITEHERE.COM NAMESERVER HERE>
tracert crs.ultradns.net
Step 3: Source IP(s)
Providing your source IP will help in determining the route taken from point A (where the DNS request originated) to point B (the zone experiencing DNS issues).
- Open a browser and visit https://www.whatismyip.com
- Provide the link with numbers next to My Public IPv4
Additional Information