Question: I have recently setup Wordpress Multisite and have that working well. Now to complete the branding, I want to use `feeds.mydomain.com` for the MyBrand integration to Feedburner. I have setup the CNAME to point to the server that Feedburner has specified, but when I visit the site (after ensuring the entry could propagate), WordPress takes over thinking I want to create a new website. I am guessing this is a DNS issue, but I am not sure where to begin to troubleshoot this further.

Answer: 
This is probably a DNS issue. Make sure `feeds.mydomain.com` points to Feedburner. You can easily check it running a DNS query.

With Linux/MacOSX, use the `dig` command.

```
$ dig feeds.engadget.com

; <<>> DiG 9.6.0-APPLE-P2 <<>> feeds.engadget.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19666
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;feeds.engadget.com.        IN  A

;; ANSWER SECTION:
feeds.engadget.com. 2010    IN  CNAME   weblogsinc.feedproxy.ghs.google.com.
weblogsinc.feedproxy.ghs.google.com. 28 IN CNAME ghs.l.google.com.
ghs.l.google.com.   200 IN  A   74.125.77.121

;; Query time: 78 msec
;; SERVER: 85.37.17.16#53(85.37.17.16)
;; WHEN: Wed Oct  6 20:56:36 2010
;; MSG SIZE  rcvd: 118

```

You can also run a DNS query using an online service, e.g. [DNS Query](http://www.dnsqueries.com/en/dns_query.php). The DNS response should be a CNAME record pointing to `ghs.l.google.com`. If it is an `A` record, the DNS hasn't been property set.
It's definitely a DNS cache issue. I just tried a different computer and it worked. I didn't think about that until after I posted this.