Custom Name Servers Setup is often a searched item by a niche of webmasters, mainly for branding. Here is a guide on how to setup Custom Name Servers. We are taking that, you are quite used with the basics of Name server itself. There are many points you must know before proceeding to use Custom Name Servers.
Information about Custom Name Servers
The basic thing is, if your NS set are – dns1.stabletransit.com and dns2.stabletransit.com, quite obviously you have set up them from your Domain registrar control panel and these were provided by your web hosting brand. In our example, these set belongs to Rackspace. Now if you domain name is example.com, then you are wanting :
dns1.example.com
---
dns2.example.com
as your pretty looking Custom Name Servers. This Custom Name Servers are also known as Vanity Name Servers. If you are using Rackspace Hosting with their service as domain registrar, then it is better to ask whether Custom Name Servers can affect the performance. The setup (of server) can be different for Cloud Servers and Cloud Hosting, especially if Load Balancers are used.
There is no known SEO benefit of having Custom Name Servers, as basically you are just shielding the real NS from human (not sure how many will look for it though), the whole system of Internet will understand its nothing but you have just worn a scarf.
Steps for setup of Custom Name Servers
If you are using Rackspace Hosting with their service as domain registrar, then it is very easy. Go to clickandname.com account and create custom name server set :

Quite obviously, you will need to add these set to your name server of the domain. These are very simple two step procedure in case of Rackspace plus when domain name is under Rackspace (registered or transferred). We guess, the steps to add Custom Name Servers are such simple, when both are from the same brand.
A bit difficult situation is when domain registrar and web host are different. Then you need that Custom Name Servers to be authorized from your domain registrant first. Otherwise I have the chance to create Custom Name Servers of your domain name! So this is a kind of check point. After this point is done, change name servers value for your domain from the hosting end to point towards.
More advanced is your control panel and DNS system, more it will be easy to add Custom Name Servers.