Ping fails but nslookup works
nslookup, the IP can be returned. But when performing
ping, return following error
ping: cannot resolve <hostname>: Unknown host
Second DNS server issue
The second DNS server isn't resolving the IP address.
Another DHCP server issue
Another DHCP server provide different DNS server.
killall -HUP mDNSResponder
DNS lookup fails but nslookup works
Using wildcard DNS record
Using wildcard in DNS A or CNAME can reduce maintenance work, but this also has some drawback.
Updating DNS will take time, not only needs time to edit DNS entries, but also the DNS broadcast time, which can take more than 30 minutes to update an existing entry in other DNS server, and some DNS server can take even longer.
If use widecard, there is no editing requirement.
/etc/resolv.conf has entry as below
When searching for
google.com, It might hit
google.com.example.com if wildcard used, because
google.com.example.com will return IP address as same as
Without editing entry, the some DNS servers might still caching old data. For example, if you have both wildcard *.example.com and a specific entry ftp.example.com, and you decided to remove ftp.example.com, the wildcard might not take effect.
Accessing non-exist domain
If using browser access undefined domain name, and hit the web server, using NGINX can perform redirect to change URL. This can fix the issues which web coding based on current URL.
return 301 $scheme://mywebsite.tld$request_uri;
Is a wildcard DNS record bad practice?
DNS Configuration Basic
Define subdomain using IP address
A record to define a subdomain to IP
A www 192.168.1.1
Define subdomain using host
CNAME record to define a subdomain to IP
CNAME www www.example.com
Default host for all subdomains
Following record is to give IP address of www.example.com to all subdomains.
CNAME * www.example.com
Default IP for domain
Use @ in A record.
A @ 192.168.1.1
Default EMAIL server
MX mail.example.com 20
Note: The number is Priority