Tag: wildcard

Using wildcard DNS record

Using wildcard DNS record

Using wildcard in DNS A or CNAME can reduce maintenance work, but this also has some drawback.

Pros

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.

Cons

Search suffix

If /etc/resolv.conf has entry as below

search example.com

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 example.com.

Caching

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.

server {
    listen 80;
    server_name *.mywebsite.tld;
    return 301 $scheme://mywebsite.tld$request_uri;
    }

server {
    listen  80;
    server_name mywebsite.tld;
    [...]
    }

References

Is a wildcard DNS record bad practice?