I am facing a terrible slowdown & inability to access to my website from time to time after changing it's IP. Below is what exactly happened and I would be glad if an expert can tell me what might have gone wrong.
I have a dedicated server with cpanel. I was using a shared IP for the website till yesterday which was primary NS's IP. (Which also has 20 more websites under it) I had to use SSL Certificate on this website, and therefore I changed it's IP address. And, instead of creating another IP (I have been given access to 30 IP's by datacenter), I chose to assign secondary NS's IP to the website. And then, I went to domain provider and changed the order of NS's in update nameservers section (put ns2 to first, ns2 to second)
Shortly, I had: xx.xx.xxx.20 - ns1.maindomain.com xx.xx.xxx.21 - ns2.maindomain.com
on my server. Website is now pointing to xx.xx.xx.21 but occasionally cgi-sys/defaultwebpage.cgi page pops up with error. Is it something to do with DNS propagation? (It has been 12 hours) Last time I tried an ip change, it didn't take this long.
In which step might I have done something wrong that can cause the slowdown? For the future cases, could it be simpler if I just set a new IP and assign the website to it without touching to domain NS setup and secondary NS? :)
Appreciate your help,