Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!


IP renumbering, what to do?
New on LowEndTalk? Please Register and read our Community Rules.

All new Registrations are manually reviewed and approved, so a short delay after registration may occur before your account becomes active.

IP renumbering, what to do?

RaymiiRaymii Member
edited March 2012 in General

So RAMhost is soon going to give my kansas VPS a new IP.
I have a list of things to do when it changes, is it good or do I need to do additional stuff?

  • Before the change, set the TTL in the DNS of the domains to 1 hour instead of 1 day.
  • A few days later, change the IP in the DNS
  • Scan all the links and if needed, change them
  • Anything with rDNS? (mail)

Any suggestions?

Comments

  • fanfan Veteran

    I think they'll let the old IP work a while after the renumbering, so you have time to do all these. I suggest you submit the rDNS request as soon as you get your new IP, it's a manual process with ramhost I think.

  • InfinityInfinity Member, Host Rep

    There is 60 seconds TTL btw.

  • raindog308raindog308 Administrator, Veteran

    @Infinity said: There is 60 seconds TTL btw.

    ...which most DNS nameservers do not honor, alas.

  • MaouniqueMaounique Host Rep, Veteran

    Maybe setup a round-robin then, if 60 minutes is too long and they dont allow the old IP to point to same container. :P
    I dont think the links contain IP, they shouldnt. It should work only with DNS change.
    M

  • @infinity I know that there is a 60s ttl but as @raindog308 said I know of at least to providers who give you the finger if you do that.

    @maounique how would I setup a round robin? They do let the two IPs coexist for thirty days so...

  • if they let the 2 IPs stay for 30 days, don't worry about dns propagation. just change to the new one and let the traffic with the old IP cached hit the old IP until the ttl expires.

  • MaouniqueMaounique Host Rep, Veteran

    Yeah, change DNS only, dont worry about TTL, it will change when will change, 30 days are more than enough. Round-robin means seting up more IPs for load balancing usually. From your page I see you know a lot of things, wont be too complicated, but, in this case, is not needed.
    M

  • @Maounique I've got some experience with HA via heartbeat but that was in the hospital with custom built (not by me) software (a VAX/VMS emulator with TCP/IP for RHEL4). I only knew the term from the graphs that rrdtool (munin) creates.

  • I could be wrong but I believe the people suggesting a Round Robin are talking about adding an additional A name to the domain. You can have more than 1 ip for a domain. For example:

    www A 192.168.1.50
    www A 192.168.1.52

    If that was a bind config it would give two ips to www.yourdomain.com

    nslookup would display:

    Server: 8.8.8.8
    Address: 8.8.8.8#53

    Non-authoritative answer:
    Name: www.yourdomain.com
    Address: 192.168.1.50
    Name: www.yourdomain.com
    Address: 192.168.1.52

    Your browser or on windows your dns cache will choose one the first time you dns the domain. If its unable to connect it will usually go to the second. Occasionally you will have to wait for ttl to expire or in windows you may need to flush your dns cache to have it change when there is no problem reaching either ip. (ipconfig /flushdns)

    Hope that helps.

  • raindog308raindog308 Administrator, Veteran

    roundrobin really was never intended for failover - just load balancing. There's no reason to think the client (browser) will know it's RR or go back and ask for more IPs.

    I wish the standard did allow a "this is part of a cluster, if one doesn't work, try these others" but it doesn't.

  • @TheLinuxBug I've been doing that with my IPv6 enabled boxes for a while, I've got multiple IPv6 adresses in the AAA records... Now trying it on a vps with 3 IP's, see if it works. Thanks for the explanation.

    @raindog308 Hehe that would be nice, a DNS server with built in HA, failover, heartbeat and of course it supports all possible protocols to failover :p

  • @Raymii said: @raindog308 Hehe that would be nice, a DNS server with built in HA, failover, heartbeat and of course it supports all possible protocols to failover :p

    Well that exists with gdnsd, at least for HTTP.

  • ramnetramnet Member, Host Rep

    Most people in this thread seem to be severely confused, or just plain ignorant about how a typical ISP executes a renumbering plan.

    Before the change, set the TTL in the DNS of the domains to 1 hour instead of 1 day.

    You don't need to do that.

    Maybe setup a round-robin then

    Definitely don't do that.

    I think they'll let the old IP work a while after the renumbering

    This is correct.

    I suggest you submit the rDNS request as soon as you get your new IP
    don't worry about dns propagation. just change to the new one and let the traffic with the old IP cached hit the old IP

    And this is what you should do.

    if they let the 2 IPs stay for 30 days

    This is standard, and is what we are doing.

    Thanked by 2rds100 Raymii
  • Don't forget to check the various service confs to make sure they are not listening to only one of the IPs.

Sign In or Register to comment.