Advanced routing

DNScaster supports a number of advanced routing options for dynamically generating DNS responses.

  • ALIAS records

    An ALIAS record publishes both A and AAAA records on the current domain, using the IPv4 (A) and IPv6 (AAAA) records from another domain (or another subdomain on the current domain).
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  • Geo-closest (GEO records)

    GEO records dynamically return the 1-3 servers (IP addresses) closest to the user.
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  • Geo boundaries

    Geo boundaries dynamically restrict DNS responses to those inside or outside certain geographical boundaries.
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  • IP boundaries

    IP boundaries dynamically restrict DNS responses to those inside or outside certain IP blocks.
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  • Wildcard records

    Wildcards match otherwise undefined subdomains and dynamically create matching records. Wildcards are allowed on most record types.
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In most cases, two or more of the above routing options may be used in combination with one another. See individual pages for notes about combinations and feel free to get in touch with further questions.


Geo and IP accuracy

While geo locations and IP addresses might seem precise, most clients use a 3rd party DNS resolver (most commonly their ISP). Many resolvers provide what’s known as EDNS Client Subnet information to help identify the client more precisely. (For those familiar with HTTP proxies, it’s the same concept as X-Forwarded-For and the PROXY protocol.) Mapping of IPs to regions is also a moving target. Broader geo regions are generally more accurate than narrow regions. If clients and resolvers are acting in good faith, boundaries and geo locations work quite well. However, they are not suitable as a security mechanism.