1. Log into your 123 control panel and select the domain you wish to point to Zenfolio
2. Click DNS, then Advanced DNS
3. In the add new record fields, enter www in the first box, choose CNAME as the type and copy and paste the following into the last field: custom.zenfolio.com.
4. Add another record just like step 4, but this time replace the www with an @ symbol, choose 'A Record' as the type and enter the following IP address: 64.62.158.18
You should have two records like this:
www CNAME custom.zenfolio.com.
@ A 64.62.158.18
5. Save your changes
Then follow these steps (taken from the Zenfolio help page):
1. Return to your Zenfolio account and log in, if necessary.
2. Go to Preferences » Custom Domain.
3. Select "Point a custom domain name to your Zenfolio pages."
4. Enter your domain name. Be sure the domain you enter begins with www.
5. Click Test DNS Setup.