TwistedHelixis Posted March 1, 2017 Posted March 1, 2017 Hello, I am getting duplicate IP's in DNS and some IP's have a time stamp of 2008, so I want to clear it all up. This is a very simple setup with 1 DC. I have read a lot of info on the internet but would prefer to have someone walk me through the steps, so I can ask questions etc and also as I believe it's possible to accidentally delete statically set IP's, although none of the websites I have read explain how to avoid this issue. Thanks for your time
jslate1980 Posted March 6, 2017 Posted March 6, 2017 Hi if you have statically set ip addresses for servers usually I would manually create dns records for them so scavenging doesn't remove the records. Is dhcp being used to assign dns records when a dhcp lease has expired? 1
TwistedHelixis Posted March 6, 2017 Author Posted March 6, 2017 Thanks for getting back to me. Hi if you have statically set ip addresses for servers usually I would manually create dns records for them so scavenging doesn't remove the records. I have static IP's for my server, printers, routers and Wifi points. I know my way round DNS at a basic level, but have never needed to create any records - How do I manually create dns records? Is dhcp being used to assign dns records when a dhcp lease has expired? I believe so, see my screen grab.
jslate1980 Posted March 6, 2017 Posted March 6, 2017 If you pm me over your email address I will send you a copy of a document that was produced by a company we purchased some support off.
jslate1980 Posted March 6, 2017 Posted March 6, 2017 To create a static dns record. Make sure you have the ip and fqdn of all statically assigned devices. You will need to remove the dynamically assigned record first in forward lookup zones > domain name > host A record. Then right click> new host A or AAAA. Insert fqdn and ip and select create associated PTR record to create reverse record.
TwistedHelixis Posted March 6, 2017 Author Posted March 6, 2017 Would any Ip's within our DHCP reservation count as static IP's and need re assigning. I have a DHCP reservation from 1 to 25 that I normally assign my server, routers, printers etc in to, so those numbers don't get dished out, but I do have a couple of static IP's outside that range such as our WAN which is on 256.
ITGURU Posted March 6, 2017 Posted March 6, 2017 I have DHCP leases set for 30 days. Then on 1 of my DNS Servers, I have the following scavenging settings: Never had any IP issues 1
TwistedHelixis Posted March 7, 2017 Author Posted March 7, 2017 Thanks for all the help so far. I was under the impression that it was recommended to have DNS scavenging time set to a longer interval than the DHCP lease times, but everyone so far seems to have this the other way round. Does anyone have any guidance on this.
ITGURU Posted March 7, 2017 Posted March 7, 2017 I went by the microsoft recommendations that were online, but changing the period relevant to my DHCP lease. If you search for it, there is information online
3s-gtech Posted March 7, 2017 Posted March 7, 2017 From what I remember, for best results your DHCP lease should be equal to your DNS No-refresh + refresh intervals, so my lease is 8 days, no-refresh is 4 and refresh is 4. Just had to check through all this again recently as I had a mass of stale reverse lookup in place - one of my DNS servers didn't have scavenging turned on and it made a mess. Turning on scavenging, deleting the stale records and waiting for it to gradually fix/update itself across the domain now.
Koldov Posted March 7, 2017 Posted March 7, 2017 (edited) I've looked at my DNS a few times and I've got to say @TwistedHelixis I'm as confused as you... There are recommendations I guess, but as with everything there is so much variation it becomes impossible to know what is best. I checked my DNS settings and it was set to something like 30 days... Also someone on here posted recently about BPA... Which I thought might be a cool thing to do.... Until it turned my nice green dashboard RED!!! Anyway, one of those BPA errors said I should have it set to the 'recommended interval', which it turns out was 7 days, so who knows. Also interested at your comment about your DNS servers @3s-gtech. Are they on the same Domain? As I noticed somewhere on another thread it should only be enabled on one DNS server in the Domain... Not sure if I will run into trouble but actually it is on both of mine, mainly due to the BPA result complaining it wasn't set on the server I ran it on (would it even know if I had another DNS server running?). Also what makes it slightly more confusing for me is that DHCP is being run from our managed switches and I have to admit, I don't know what the lease times are set to there... Edited March 7, 2017 by Koldov
TwistedHelixis Posted March 7, 2017 Author Posted March 7, 2017 Also someone on here posted recently about BPA Sorry that was probably me. 1
3s-gtech Posted March 7, 2017 Posted March 7, 2017 The documentation I read suggested that if it's not turned on, on any server, resources on that one won't be scavenged correctly and this will then propagate across to the others. It makes sense to not do so, of course - if a resource is deleted from one server in a replicated set it will then replicate the deletion. However, I wasn't finding that, and some others have suggested the same. It's now turned on all three of my DNS servers. After all, they should just be trying to delete the same record at the same time. All DNS servers on the same domain, though we have zone transfers upstream to enable better integration of our iPads (which wanted to go out of the LAN then back in and couldn't resolve). 1
TwistedHelixis Posted March 7, 2017 Author Posted March 7, 2017 Can someone just check if they have a user account listed in DHCP DNS dynamic reg credentials - See image taken from web - Currently I just have ***** in the password fields, but the other boxes are all blank. Thanks
TwistedHelixis Posted March 8, 2017 Author Posted March 8, 2017 So far I have been testing on my test VM server. I am almost ready to attempt setting up DNS scavenging for real, but would really like an answer to my post above. Just need to know if DNS scavenging works as expected without a username and password in the DHCP DNS dynamic reg credentials, or if you do indeed have a username / domain & password listed.
ITGURU Posted March 8, 2017 Posted March 8, 2017 Mine are set to my domain admin details. the user used only needs to be a member of 'domain users' therefore I created a new AD account specifically for the DHCP Credentials. I never use the domain admin for anything - I always create specific accounts for each software/service that requires access to AD etc. 1
TwistedHelixis Posted March 8, 2017 Author Posted March 8, 2017 he user used only needs to be a member of 'domain users' therefore I created a new AD account specifically for the DHCP Credentials. Haha I was just reading that on a site when you posted.
TwistedHelixis Posted March 8, 2017 Author Posted March 8, 2017 Just created a domain user account and added it to the DHCP credentials section. Going to leave things for a week before moving on to my next steps. Thanks for all the help so far. 1
jslate1980 Posted March 8, 2017 Posted March 8, 2017 Have you added dnsproxyupdate membership to the dhcp account used? https://technet.microsoft.com/en-us/library/dd334715(v=ws.10).aspx
TwistedHelixis Posted March 8, 2017 Author Posted March 8, 2017 Have you added dnsproxyupdate membership to the dhcp account used? https://technet.microsoft.com/en-us/...(v=ws.10).aspx Looks like I do not need to add nsproxyupdate as I have a single DHCP server, but will continue to read more info about it.
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