My VPS account only has 1 IP address for webserver + nameservers. As far as I know all the hosting companies that I knew of are having separate IPs for their nameservers. I would like to find out the advantages of doing that.

The reason I ask is because recently there are a few times when accessing my clients' websites, the browser look up time for the websites seems to be quite long and sometimes page can not be displayed. I have to try a few times such as using www or without www. But once it "found" the website, the loading is fast.

I didn't have this problem last time when my clients' websites were on shared hosting reseller account.

Please advice if getting 2 extra ip addresses for my VPS nameservers would solve the issue? Thank you.

It's doubtful that it's actually the problem, I'd look into the error logs or if it's not resolving, try running and nslookup or dig and see where the NS error is at.

Better gat additional IPs for NS1 and NS2 and one for your web server to avoid any IP conflict.

Since the two IP's would be pointing to the same VPS and using the same name server, the amount of time it takes to locate a site will be the same. It's more likely that you have a faulty name server, zone file, or incorrect routing at the network level.

The idea of having two name servers was redundancy which should equate to less potential for failure. Since a majority of sites now days use two IP's which are located on the same server or VPS there is no real redundancy.

2 IP(s) would do you just fine. Go with another hosting supplier or ask to buy a dedicated ip at your current supplier.

How much dedicated IP cost?

Depends on the company. About $1-2 per month

I dont think an extra IP would fix the problem. Where is the server located? Are you in the same country or around the other side of the globe? Also, is the server over worked? Maybe it just isnt responding as quick as needed as it finishes off another task.

Do your clients report any problems like these?

When I was in the hosting biz we had our servers in the US. I am UK based and they loaded fine for me, and the staff who were in the US. However, we had clients from South Africa who had a number of problems with DNS on our hosting and just general browsing around a lot of sites. We ended up putting a DNS server in SA to speed up their queries which seemed to work well.

With customers say from the Africa you might have payment related problems. Matt have you had such ones I wonder?

It depends which part of Africa. Some places were just fraud problems while others were just fine. The main reason I mentioned Africa though was due to network issues in them contacting our US based DNS servers. The solution was another DNS server closer to them that could respond quicker for them.

The additional IP would only rectify an issue caused by the domain registrar needing a second IP, most likely for failover reasons.