Howdy,
The best way to map a domain to a WordPress.com blog is to set your domain's nameservers to the following values:
NS1.WORDPRESS.COM
NS2.WORDPRESS.COM
NS3.WORDPRESS.COM
However, if your registrar requires that you create A records, please note that our IPs change over time. Because of this, your domain might stop working at some point in the future. If that happens, please get in touch with us to find out the most current IPs and then update your A records accordingly.
If you still want to go ahead and map your domain using A records, please be sure to create at least two, pointing to two different IPs from the list below:
72.233.2.58
76.74.254.120
74.200.244.59
74.200.243.251
76.74.254.123
72.233.69.6
I hope that helps!
