Nameserver problem

January 7, 2005 4:59 PM

Help! My webmaster's out of town and I don't know how to do this....

I just changed our nameservers to go to a new hosting service.

How/where do I check to find out when they're actually "resolved" to the new host?

I'm sure I got the syntax wrong. Basically I need to know when our site is pointing to the new server so I can set up email accounts, but have no clue about how to do that.

(The new host is dreamhost, if that helps.)

Thanks much!

posted by mudpuppie to Computers & Internet (8 answers total)

You can do it from the command line, but since I don't know your platform a web-based nslookup utility should do the trick.
posted by savetheclocktower at 5:08 PM on January 7, 2005

When I've changed name severs, it just took a few days for it to propagate all the way down to all the different dns servers. I checked by pinging the site to find the IP and making sure it was the new server. From a DOS prompt it would be "ping yousitenamehere.com" and look at the IP. Hope that helps.

(also, it won't change for EVERYONE all at once, AFAIK)
posted by theFlyingSquirrel at 5:10 PM on January 7, 2005

Response by poster: Okay, so I've done that. It shows the new servers. Does this mean the domain is "resolved"? What does "resolved" mean, anyway?
posted by mudpuppie at 5:12 PM on January 7, 2005

Response by poster: Oops -- squirrely, that helped. Thanks.

Pinging I can do.
posted by mudpuppie at 5:13 PM on January 7, 2005

Depending on the cache timeout of your old zone record, it could take up to a week for you to see the new IP address from your personal internet connection.

But to check:

nslookup www.yourdomain.com

from the command line of any modern operating system will tell you what IP address www.yourdomain.com resolves to.
posted by cmonkey at 5:15 PM on January 7, 2005

Response by poster: thanks, folks. big help.
posted by mudpuppie at 5:17 PM on January 7, 2005

The issue here is that changes to IP addresses take a while to propagate across the net, so even if your ISP has the new info, not everyone else in the world will necessarily get it at the same time. This is because when, say, machine X at ISP Y looks up your site, it stores that information for next time so it doesn't need to look it up again, saving time and bandwidth. Different machine have different settings for how long that information remains so it's impossible to predict how long propagation of new information will take.

In other words - don't assume that everyone will be able to see the new server for about a week. Though they probably will within 24-48 hours.
posted by Sparx at 2:38 AM on January 8, 2005

You actually can control how fast the DNS "propagation" lasts. The term is called "time to live" or TTL. Most DNS servers default to a TTL of 24 hours. Services that provide "dynamic DNS" typically have a TTL of 5 minutes or less. The caching DNS servers at the ISPs should honor this TTL and should only cache for that long. Unfortunately, most hosting providers won't let you change your TTL from their default values. Changing your TTL now won't help you, as ou have to plan in advance. Setting your TTL back to 5 minutes won't do any good if there's already caching servers out there with your old address and its 24 hour TTL.

There's one TTL that you have no hope of controlling -- that of the big daddy root DNS servers for .com, .net, .org, etc. The records on those servers are the ones that actually point to the name servers for your domain. They have a TTL of 48 hours. If you have indeed changed name servers for you domain, you may have to wait that long.
posted by zsazsa at 11:12 AM on January 8, 2005