This is of course a very bothering question rattling in our mind, when we are planning to do a DNS change and already has spend so much of time to make better ranking continuously. Yes! People wants to know this: "Does change of IP address of my site affects my ranking". Based on my study and observation, I would say, it does NOT. But yes, there may be some other related factors, while doing so. Lot of topic is readily available just a click away in Google, but here i will just discuss what i have understood based on something which I have experience on the above subject line.
Before considering an IP address for your domain, you should have a check list to actually give a go ahead if that IP should be allowed to map against your website. If its a web-host company, make sure, this ip is NOT banned in various search engines due its possible spamming or some other such notorious activity.
If it is you own company, make sure this IP was not used for some Email server/ Crawler and you are still fighting to get your reputation in the market.
If it is a web-hosting company, you need to also check the up-time of their server/services, as it matters a lot when a spider or crawler finds it down while trying to access your site. Also some web-hosting companies block spiders, to save their bandwidth. For this you can ask the webhost companies to provide some sample sites and do check their ranks in google or any other Search Engine.
After doing some good no. of migration, let me jot down a few very imp. points, that might help :
1. Do not change any URL. First migrate or do a cut over as it is. This is true for any migration. "Architecture change and migration should NOT be combined" - that's what I believe.
2. Make sure, the site does not go down quite often, at least at that change window, else people around will have mix reaction while identifying the issue for lower SERP, that's what i faced in my career. RCA is time consuming.
3. Keep the site available in older server also for some time. You can decide until when , by seeing the access logs.
4. Make sure all the links are healthy and opening in your site. There is a free online tool for this.
5. Test...and.. test! After site launch, run a “site:www.yoursite.com” search on Google and click on the links to be sure that everything is behaving just the way you – and your end user expects.
6. The Change of DNS to point to your new web host is the actual crux i would say. With a short TTL, you could pull a data center’s IP address out of the rotation in just a few minute. This is very crucial for sites who keeps a very high TTL, which needs to be calculated well in advance and reduced prior to DNS cut over. Doing so helps everyone to move to your new IP address in short order instead of having a mish-mash where some people are using the old IP address for hours, which will place you in much better shape.
7. Wait for the DNS changes to propagate through the web,(its like a wave!) you can use you can use the “dig +trace domain” command in Linux/Unix. The “+trace” option tells dig to go all the way up to the DNS root servers for the lookup. Once changes are visible, you can just wait untill TTL expire. Remember that DNS is cached at each level, so even if you clear the cache, your ISP probably has cached the previous IP address until the TTL expires.
8. Once you are sure users or are fetching from the new webhost/IP address, you’re done. You can probably shut down the old web service of the previous version of the site. You might have to spend some time checking for inlinks from other sites and making sure that they are still functioning. If necessary, you may need to set up 301 redirects. Access logs on your site would be a better place to start.
That's it. Believe me with these few precaution, change in IP will cause no SERP low rank.