Question: While querying `www.audi.de` using dig, I get the following response:

![dig's response](https://i.stack.imgur.com/M1PiI.png)

Google's `8.8.8.8` DNS server is returning a different A record, what is the reason for this? Does it have anything to do with `www.audi.de` using a CDN?

Answer: 
Yes, many CDNs use "GeoDNS" as one way to distribute traffic. Akamai call their implementation ["Global Traffic Management"](https://techdocs.akamai.com/gtm/reference/api):

> 
> In the most traditional usage, a query's answers are static. Someone types the answers into a configuration file, and the answers change only when the file changes.
> 
> 
> A dynamic DNS system computes and returns answers on the fly. This can vary from one query to the next. A typical usage returns the IP address of a server assigned dynamically through dynamic host configuration protocol (DHCP). This address changes, which is common with most home Internet connections.
> 
> 
> Global Traffic Management (GTM) is a dynamic DNS system that manages traffic to your data centers. From one moment to the next, GTM chooses the best answers and returns them to client name servers in response to their queries about your domains.
> 
> 
> 

Many public resolvers even support an EDNS0 feature called "Client Subnet" which reveals to the authoritative servers (Akamai's, in this case) which client sent the original query – rounded down to the /24 or /64 – so the answer *may* be tailored to your location even though you think you're hiding behind a public resolver. (Google Public DNS [seems to](https://developers.google.com/speed/public-dns/docs/ecs) support ECS, though Cloudflare's 1.1.1.1 DNS does not.)

Finally, the CDN's authoritative nameservers might simply return different answers *at different times* for the same location (e.g. for balancing load among individual hosts). So if one resolver just got fresh data but another already had it cached from 3 minutes ago, their answers could still be different.
A website can be configured with multiple A records, and this is not
a problem.
The aim is to do round-robin load-balancing for high-availability.

If multiple A-records are defined for a domain, they are returned in
a round robin-order by DNS servers.

Almost all browsers will receive the full list of A records and will
check others if the one that is used fails, and you will see waits
between tries until a working IP is found.
The browser will then cache which address is working and continue using
that one for future requests unless it also fails, and then it will
search through the list again.

For more information see:

* [Using multiple A-records for my domain - do web browsers ever try more than one?](https://webmasters.stackexchange.com/questions/10927/using-multiple-a-records-for-my-domain-do-web-browsers-ever-try-more-than-one)
* [How To Configure DNS Round-Robin Load-Balancing For High-Availability](https://www.digitalocean.com/community/tutorials/how-to-configure-dns-round-robin-load-balancing-for-high-availability)