DNS propagation !

Discussion in 'Site & Server Administration' started by egexa, Aug 14, 2010.

  1. #1
    hi,

    I had a hostgator shared account before which was hosting my 6 sites with 40 subdomains, everything was ok.
    One month ago (Jul,15) I moved to a new VPS with 2 dedicated IPs then I setup 4 name servers on godaddy and updated my domains to point to them.

    Well now most of my subdomains point back to the old IP of HG servers. At the first I thought that it's the DNS propagation, but it's impossible to last for one month now!!

    I got messages from many users around the world that sometimes they get dns errors on my sites. The solution is to run flushdns, but It's not possible to tell all the users to make it, also the error may appear again after couple hours.

    I tried to decrease the TTL of my domains and their subs, I added new IP, changed the nameservers again but no hope!!!

    Could anyone here help me to understand this strange issue?

    Thanks.
     
    egexa, Aug 14, 2010 IP
  2. RHS-Chris

    RHS-Chris Well-Known Member

    Messages:
    1,007
    Likes Received:
    35
    Best Answers:
    10
    Trophy Points:
    150
    #2
    Plug a couple of your sites in here, odds are you have some errors with your DNS health:

    http://intodns.com

    Chris
     
    RHS-Chris, Aug 14, 2010 IP
  3. hans

    hans Well-Known Member

    Messages:
    2,923
    Likes Received:
    126
    Best Answers:
    1
    Trophy Points:
    173
    #3
    I had a similar IP related DNS problems in recent weeks after new servers installed (on my own servers / NS servers):
    to solve:
    have a look at your registrar DNS settings
    you enter your NEW NS - BUT ( my mistake ) I forgot the find the special form that allows to change the IP for each new NS !
    if you use additional NS slaves - make sure there too you modify/adapt the NEW master-NS_IP

    a correct parent NS entry has your ns.your_ns_server.tld PLUS the correct IP
    else
    you change your ns names but keep NS IP and within a few days you get less and less traffic !!

    within a very few hours after my own a.m. corrections made, all global traffic was back to normal.
     
    hans, Aug 15, 2010 IP
  4. egexa

    egexa Active Member

    Messages:
    14
    Likes Received:
    0
    Best Answers:
    0
    Trophy Points:
    86
    #4
    it shows me some errors and i could solve them, thanks.
    is there a tool to check if dns propagates correctly from different places ?
     
    egexa, Aug 15, 2010 IP
  5. egexa

    egexa Active Member

    Messages:
    14
    Likes Received:
    0
    Best Answers:
    0
    Trophy Points:
    86
    #5
    yes i changed the ip in godaddy, but don't know what's problem !
    i guess that's because i use 1 NS server so if it's down for a moment it'll give error :S
     
    egexa, Aug 15, 2010 IP
  6. hans

    hans Well-Known Member

    Messages:
    2,923
    Likes Received:
    126
    Best Answers:
    1
    Trophy Points:
    173
    #6
    your
    however proves that you have NO new IPs in your PARENT ns records
    once you really have updated/replaced OLD NS IP with new ones, there is NO way that a NS shows up old IP again after all NS propagation is done ( some 1-2 days in most cases ) but a very few hours for most of the traffic

    it certainly would save US substantial time if you would give precise site name / ns URLs for the problem posted!!

    to change your zone files, etc alone changes nothing at all
    of course you did after each change a:

    - change serial number of NS then
    - rndc reload
    - and if you add/change zone files or named.conf, then also a complete name server restart

    to make all new records active
     
    hans, Aug 15, 2010 IP
  7. egexa

    egexa Active Member

    Messages:
    14
    Likes Received:
    0
    Best Answers:
    0
    Trophy Points:
    86
    #7
    yes i understand this and made all these steps. look at this
    my main domain egexa.com > 69.175.74.76 use the following NS:
    ns1.egexa.com > 69.175.74.76
    ns2.egexa.com > 69.175.74.71
    ns1.egexa.net > 69.175.74.76
    ns2.egexa.net > 69.175.74.71

    these are the true values which should work properly, however sometimes my subdomains under egexa.com (eg movies.egexa.com) point back to the old IP of HG 174.120.154.199 so gives 403 error on the old account.
     
    egexa, Aug 15, 2010 IP
  8. hans

    hans Well-Known Member

    Messages:
    2,923
    Likes Received:
    126
    Best Answers:
    1
    Trophy Points:
    173
    #8
    1
    multiple NS on same machine makes no sense at all
    also on multiple machines same subnet makes little to no sense

    2.
    best (unwritten law?) 3 or more NS on 3 different subnets

    example:
    = one on your own machine as master

    plus 2 slaves on zoneedit.com
    = 3 NS on 3 machines / 3 subnets

    3
    a NS NEVER ever should be down at all
    thats why we have 3 or more - to have at least 2 NS running if one is maintained or down

    4.
    TTL
    in my experience if you change all system = domain and NS change IP
    you may expect the vast majority of traffic to move to new IP within minutes and be done within 6 or so hrs
    maybe 80-95% of all traffic may arrive on new machines after 24 hrs

    but
    there is a remaining generic traffic arriving up to several weeks on OLD IP for the simple reason that there are still some ISP updating their NS every many days or even weeks. I made such experience even in high tech countries (central europe with major ISP)

    hence

    if you do ALL correct
    you still have lost traffic unless you plan such a major move many weeks ahead and

    run OLD site several weeks into full operation of NEW site until you see that there no longer is generic human traffic arriving at OLS IPs ( tail -f /var/log/apache2/access_log )


    in your case - too late. but if you sure you did all correct NOW
    then you just have to ride it out until all ISP-NS point to new IPs

    meanwhile you may reconsider above slave NS to add more stability to your NS network

    myself i have one domain running (round robin) on 3 servers/2 subnets
    each server has 1 NS plus total 2 slaves = total 5 NS on 4 subnets
    that leaves me sufficient room for major system upgrades with at least 2 fully configured servers up at any given time.

    I have checked some of your subdomains and found only current NS data
    some of the current warnings you have in http://intodns.com may disappear if you add 2 slaves on totally different IP subnets
    currently you probably have all your NS on one single machine .....
     
    hans, Aug 15, 2010 IP
  9. egexa

    egexa Active Member

    Messages:
    14
    Likes Received:
    0
    Best Answers:
    0
    Trophy Points:
    86
    #9
    yes i guess that it's because just one NS. i've contacted my server admins to ask them for a new ip with different subnet. i'll see if it's possible to do so.

    thank you hans :D
     
    egexa, Aug 15, 2010 IP