General discussion

  • Creator
    Topic
  • #2236893

    DHCP for Servers?

    Locked

    by mtm1208 ·

    I being asked to evaluate implementing DHCP for servers…. i think its not going to happen but need some meat to say no. I see from searching that industry wide most only use DHCP for clients

All Comments

  • Author
    Replies
    • #2627036

      Here’s the problem with using DHCP assigned addresses for servers

      by big ole jack ·

      In reply to DHCP for Servers?

      Your servers will be changing their leased IP addresses frequently or infrequently, depending on the lease duration, and will create a management nightmare unless you have DHCP integrated with DNS so that the A records are constantly updated with the new IP address when a server renews its leased address. Not only is this impractical, it creates an administrative nightmare because you have to ensure that your A resource records stale out quickly and are updated immediately. Now, taking account latency across WAN links and replication traffic, you’ll be pulling your hair out because your clients will be communicating to the servers using expired IP addresses still in the local cache. You’ll be forever instructing your users to run ipconfig /flushdns everytime they can’t access a server. Servers should always be assigned static addresses because there is just too much uncertainty involved in allowing servers to get their IP addresses dynamicaly. Also, troubleshooting will be a nightmare because you’ll never know what the current IP address of the server is unless you do an nslookup or look at the DHCP scope assignment table.

      Another issue is that if your DHCP server is unavailable for whatever reason, your servers will be sending DHCP discover broadcasts and wil eventually give up, assigning themselves a non-routable APIPA address in the range of 169.254.x.x. This will work for servers on the same physical lan segment, but realize that since there is no default gateway assigned, your server to server communciation infrastructure has just gone to crap because you don’t have a default route to communicate to and from the server.

      A third reason is that by using static IP addresses, your LAN switches won’t be overloaded by constantly having to update their ARP tables everytime a server gets a new IP address. It’s bad enough the clients are keeping the switches busy with ARP table updates and convergence issues, but now the servers will add to the workload.

      Simply put, it’s not practical for servers because it increases the total cost of ownership and administration.

      • #2626925

        DHCP for servers

        by rfink ·

        In reply to Here’s the problem with using DHCP assigned addresses for servers

        You could set up DHCP reservations for your servers.

        • #2626731

          Yes, but what if DHCP server is down? You get APIPA nightmare

          by big ole jack ·

          In reply to DHCP for servers

          It’s just not practical to have servers get their IP addresses via DHCP.

      • #2626817

        DHCP for Servers?

        by mtm1208 ·

        In reply to Here’s the problem with using DHCP assigned addresses for servers

        Big Ole,
        Thanks!!! this is exactly what i needed…

      • #2611671

        DHCP – this is a real project

        by mtm1208 ·

        In reply to Here’s the problem with using DHCP assigned addresses for servers

        couldn’t we use DHCP to assign initial IP addresses to a server at build time, but assign them as permament?

        We are trying to avoid manually keying so we can build servers anytime, day or night, and not expose us to manual intervention…

      • #2604612

        WHAT?!?!?!

        by jayson.allen ·

        In reply to Here’s the problem with using DHCP assigned addresses for servers

        There is honestly no issue with enabling DHCP on servers. Setup the service to renew addresses ever 15-30 days, and setup reservations for each server so they get assigned the same IP. As for the “if the DHCP server goes down” arguement, think of one thing….what else is going to be affected if DHCP goes down? THE CLIENTS! If your service goes down, the clients will also be exposed to the same issues and cannot connect to the server. What does a normal IT person do when their DHCP server goes down or isn’t working? They fix it immediately…. LOL! I wasn’t too cracked up about doing this on a network till I really put some thought into it. Makes management easier that’s for sure…

        • #2512857

          DHCP – WHAT

          by mtm1208 ·

          In reply to WHAT?!?!?!

          Thanks… havent heard anyfeed back from my document to management on this… so its dormant for now…

    • #2626878

      Who asked you to evaluate that?

      by genera-nation ·

      In reply to DHCP for Servers?

      Are you the New Guy?

      • #2626815

        DHCP

        by mtm1208 ·

        In reply to Who asked you to evaluate that?

        Dam, how did you know!! new to the Open systems section anyway….

      • #2626726

        I think his managers are busting his chops with this silly project

        by big ole jack ·

        In reply to Who asked you to evaluate that?

        because nobody I know of, at least mentally sane, would setup servers to acquire their IP addresses via DHCP. I have come across companies that are still statically assigning IP addresses to client PCs’ and such places get a quick tongue lashing from me and a good smack upside the head. There should be no reason to run around and keep track of statically assigned IP addresses for client PCs’ because client PCs’ should be considered as commodities that can be easily swapped out and replaced. Servers on the other hand are a different story.

    • #2627489

      Bad, Bad Idea

      by bfilmfan ·

      In reply to DHCP for Servers?

      Dennis Hopper-level bad idea!

      You didn’t state the server OS, but if you are talking to a Microsoft OS-based workstation at any point, you are going to have some serious issues with caching of the NETBios information on the workstatations.

      Do NOT do this….

      • #2627150

        Easy Rider

        by mtm1208 ·

        In reply to Bad, Bad Idea

        Agreed, thanks. Its Linux we are talking about.
        I got more insight into this now. We do our builds using a CD and then access and aduva server for the profile info. The admin puts in the ip address, sbmask, etc. They dont want us to do this anymore during normal business hours, “no plumbing of network info, except during the downwindow”. So, i believe the thought was, if the server could get the IP from DHCP it would stop human error (which of course happened). Many projects are getting delayed now due to this restriction..

        • #2628463

          DHCP has its ups and downs

          by chris_atb ·

          In reply to Easy Rider

          just like everything else to do with networking, DHCP also has its strengths and weaknesses, ill try and give you a few fair points, but forgive me for being biased as ive been trained to use DHCP ^^

          a few of the good points about DHCP

          * it’s sufficiently fault tolerant
          * it makes everyones life easier providing its used properly
          * it pushes out the information you want to give to clients in an efficient (and more to the point dynamic) manor
          * you can easily set up DHCP zones, restrictions and reservations to suit the configuration needs of the clients

          but for servers, its not recommended at all, use static 😉 the very idea for it being used on servers is flawed for one basic reason, servers ARE STATIC! 😀 they go nowhere and are rarely rebooted, so why in ja’s name would they need DHCP, they also provide services which again is a big no-no when using DHCP as other machines rely on that server.

          still if your using DHCP for clients, its best to restrict the IP addresses those servers use 😉 or one day you might find yourself in a whole heap of trouble, peace dude 😀

    • #2628161

      check this

      by vsharma ·

      In reply to DHCP for Servers?

      hi
      i am vijay

      i think this is not gud

      becoz there can b many problms

      1. lease

      2. DHCP failure

      3. DHCP down

      4. Client Discover problem

      5. if DHCP down it will take APIPA

      6. many more

      so best if u will try to use dhcp only for clients not for servers

      • #2612227

        But what if i used Automatic allocation

        by mtm1208 ·

        In reply to check this

        Vijay,
        instead of dynamic. Doesn’t that in effect stop leasing activity all together? Even at reboot time? why would a re-allocation need to take place?

Viewing 3 reply threads