1. Log in to your registrar account

The registrar is where you originally purchased the domain. If you don't remember who your registrar is, you can use whois.net to find out.

2. Locate the Control Panel or Domain Manager of your domain in your registrar account.

 The control panel allows you to change the DNS records from the default ones provided by the registrar.

Different registrars may have different control panel layouts and other names for it as well. You might find it under 'DNS Manager' or 'Domain Manager".

3. In your registrar's Control Panel, change the A record and the CNAME:

Add an empty (@) A record, with the value of 174.129.25.170

Add a  'www' CNAME, with the value of imxprs.herokuapp.com

 

Make sure to SAVE these changes. 

Few important notes:

1) It may take up to 24 hours for these changes to propagate worldwide.

2) If there are previous A records in your DNS settings - make sure to delete them.

 

Resources to change A & CNAME records on different domain registrars:

Godaddy:

Changing A records - https://support.godaddy.com/help/article/680/managing-dns-for-your-domain-names (here's a video on how to do it - https://www.youtube.com/watch?v=QNklh54mK7A)

Changing CNAME - https://support.google.com/a/answer/47610?hl=en

NameCheap:

Changing A records - https://www.namecheap.com/support/knowledgebase/article.aspx/319/78/how-can-i-setup-an-a-address-record-for-my-domain

Changing CNAME - https://www.namecheap.com/support/knowledgebase/article.aspx/1031/2/demo-how-to-set-up-a-cname-record

Register.com:

Changing A records - http://www.register.com/customersupport/tutorials/update_ip.rcmx

Changing CNAME records - http://www.register.com/customersupport/tutorials/cname.rcmx

Network Solutions:

Changing A records - http://www.networksolutions.com/support/a-records-ip-addresses-2/

Changing CNAME records - http://www.networksolutions.com/support/cname-records-host-aliases-2/

Name.com:

http://support.name.com/entries/21479548-How-do-I-create-A-records-to-point-to-the-IP-of-my-web-host-