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ip address problems

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Last Modified: 2012-05-11
I am having an ongoing issue in one of my clients offices. Lately anytime someone gets a new dhcp ip address they are unable to go on the internet. I have to give them a static ip and everything works fine. I had dhcp warnings about a month ago stating " I have used 81% of dhcp scope" so I increased the scope to add another 50 addresses. This should be more than enough for this office. We have about 30 pc's, 20 ip phones, various printers and network devices, for a total of about 100 ip's. The scope range is 200 ip's. I am assuming i have an ip problem here. I may be way off in assuming this. Any thoughts?
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Commented:
What is your router?  Do you have an old cisco in place that only has so many user licenses.  Another thing is how long does it take for the ip to be released and refreshed on the server (lease time).
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Commented:
Goes ping to uitside by using IP and url?

ping 8.8.8.8
ping www.google.com

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Commented:
The firewall is about 5years ols its a watchguard firewall. It has unlimited users to access internet. I can ping only internal network, not internet

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Commented:
IP lease time is 8 days
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Commented:
Can you ping your router ?

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Commented:
I will get back to you ASAP on that . The user left his office for a meeting. I will post my results this afternoon. Thanks for the fast response.
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Commented:
Check one time again your DHCP scope. Verify that the client gets right Subnet Mask, DefaultGateway and DNS  IP's. Verify subnet mask on the router LAN setiings.

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Commented:
where can I see which dns address is given in scope properties? I can see the scope is set to update (A) and (PTR) records dynamically. Basically, everyone who has had an DHCP address usually renews with the same address. In this case I have a mobile user with a laptop who plugs in in the morning. Currently everyone else in the office are OK. Some have renewed their lease this morning. If I give this laptop user a static ip, he's good. This is not practical in his case since he is in and out of the office regularly

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Commented:
I will check his address settings again when he gets back to office. Last time I checked tho, his ip settings all looked good, DNS, subnet, ip, default gateway all checked out.

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Commented:
ok. his ip, dns, subnet mask, and default gateway are good. I can ping and access all resources inside the network including the router.This is so annoying. Why in the world would this work when I give him a static ip? but not DHCP!

Commented:
Note down the addresses your DHCP is handing and use the same addresses when setting static ip. Is the same thing happening?

Which router do you have? Can you confirm that there are no access lists active on your router?
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Commented:
Ravakl,
You were right on! Thanks for your quick responses. We somehow had a another DHCP giving a small block of IP's which conflicted with our main DHCP server. Your advice was most helpful. Our VPN server was the culprit. I have adjusted our IP scope and all is beautiful again.
Thanks again!
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