DHCP and High Availability
This isn't so much a question as it is an attempt to beg Microsoft to consider a basic problem that I think most administrators face... DHCP availability. We never think about it until we need it, but the service is the foundation of almost any network, and yet the high availability options are the same options that have existed for the last fifteen years (at least). The standard answer to DHCP HA is to stand up two and split the scope 80 / 20. This works great on paper and never works in practice. This implementation always leads to one of two places: Scopes get over utilized so that you don't have twenty percent free. That of course is not an emergency to management until the network is down. Who ever maintains the scopes is generally a bit over worked and doing the job as an after thought, and you run into inconsistencies between the two servers. In fact I have never seen two DHCP servers that were properly configured six months after they were implemented... Having a discussion with management about DHCP and the importance of this service is like talking to the wall. It is a technical problem, not a management problem. They don't want to hear about these issues, and they don't understand them. They do however want someone's head on a plate when a major part of the business is affected by an outage. So I have come today to beg for some kind of a solution to this. Some way for DHCP servers to share lease information so that you have full redundancy. Optimally, some way for DHCP to have two or three servers at different locations that replicate lease information at the scope level. I understand that replication through AD probably isn't the answer because of replication delays between sites, but it just doesn't seem like it should be that difficult to create a mechnism where one dhcp server sends notification messages to a second or third DHCP server that an address is being reserved or leased. That way you can have multiple servers with the same scope information. Even if we could just have two DHCP servers on different subnets (and by extensions different locations) would make all the difference in the world to a network experiencing issues with a DHCP server. Easy is probably not the right word... I understand that there are issues with offline servers coming back on line and getting systems syncronized for the first time and keeping them that way under a variety of conditions, but it just seems like this service is well best overdue for an upgrade... I don't know any company or organization that wouldn't want this capability.
September 20th, 2011 11:42am

In Adddition, DHCP High Availablity 1. DHCP Cluster http://technet.microsoft.com/en-us/library/cc778572(WS.10).aspx http://technet.microsoft.com/en-us/library/ee405263(WS.10).aspx 2. DHCP Rules http://oreilly.com/pub/a/windows/2004/04/13/DHCP_Server.htmlBest regards Biswajit Biswas Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights. MCP 2003,MCSA 2003, MCSA:M 2003, CCNA, MCTS, Enterprise Admin
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September 21st, 2011 4:10am

For a previous customer I had a web developer create an HTA web page that configured the server scopes when creating new ones. I have also used NETSH to reconfigure smaller environments. When you got 200 scopes though it gets pretty difficult to adjudicate everything... I appreciate the options and I am marking you as the answer, but I had this information already. I just know sometimes the product group sees these posts, and I want to make my voice heard. If enough people note their support for this suggestion, maybe the product group will look at options to improve this service. I know clearly what the options are... I would just like to see the service improved.
September 21st, 2011 9:05am

You probably already know this too, but if you have that many scopes you have to work on, Microsoft DHCP is probably not the best option. There are a lot of products out there that integrate well with active directory and use a distributed database so you don't have to monkey around with split-scopes, etc. Some products that come to mind are: Infoblox, Cisco Network Registrar, Alcatel VitalQIP and a host of others. I regard Infoblox as the best of the ones I've played with. I know that management doesn't get too excited about DHCP, so getting funds to buy another product when Microsoft builds-in DHCP services might be a tough sell, but I think it's an important one to go to bat for.
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October 23rd, 2011 8:22am

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