Is it possible to have SSL certificate for IP address, not domain name?
The short answer is yes, as long as it is a public IP address.
Issuance of certificates to reserved IP addresses is not allowed, and all certificates previously issued to reserved IP addresses were revoked as of 1 October 2016.
According to the CA Browser forum, there may be compatibility issues with certificates for IP addresses unless the IP address is in both the commonName and subjectAltName fields. This is due to legacy SSL implementations which are not aligned with RFC 5280, notably, Windows OS prior to Windows 10.
Sources:
- Guidance on IP Addresses In Certificates CA Browser Forum
- Baseline Requirements 1.4.1 CA Browser Forum
- The (soon to be) not-so Common Name unmitigatedrisk.com
- RFC 5280 IETF
Note: an earlier version of this answer stated that all IP address certificates would be revoked on 1 October 2016. Thanks to Navin for pointing out the error.
According to this answer, it is possible, but rarely used.
As for how to get it: I would tend to simply try and order one with the provider of your choice, and enter the IP address instead of a domain during the ordering process.
However, running a site on an IP address to avoid the DNS lookup sounds awfully like unnecessary micro-optimization to me. You will save a few milliseconds at best, and that is per visit, as DNS results are cached on multiple levels.
I don't think your idea makes sense from an optimization viewpoint.