# DHCP issues



## yrana2002 (Sep 16, 2011)

My college network employs a DHCP server to assign ip addresses to systems based on whether the MAC address of the system is registered in their database( we have to register it seperately). So practically speaking, each system gets assigned the same ip addresses everytime.
Earlier, using DHCP my computer used to join the network with a specific ip everytime (192.168.193.155 for instance). Is it valid if instead of obtaining address repeatedly by DHCP client, I statically assign the same ip, subnet, gateway addresses to my system that were given to me previously? Would that permit me to enter the network?


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## mithun_mrg (Sep 16, 2011)

if ur mac is added to the router or the radius server whichever applicable then i think it will but again there r risks of conflicts so better off let the dhcp assign the address


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## FilledVoid (Sep 16, 2011)

> Earlier, using DHCP my computer used to join the network with a specific ip everytime (192.168.193.155 for instance). Is it valid if instead of obtaining address repeatedly by DHCP client, I statically assign the same ip, subnet, gateway addresses to my system that were given to me previously? Would that permit me to enter the network?


Technically yes it should allow you to access the network assuming that the router has a rule stating that your MAC Address has a reserved IP Address set. Also if the above rule is applied to the DHCP server then no there will be no conflicts as it will not assign any IP addresses that have been reserved otherwise.


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## asingh (Sep 16, 2011)

yrana2002 said:


> My college network employs a DHCP server to assign ip addresses to systems based on whether the MAC address of the system is registered in their database( we have to register it seperately). So practically speaking, each system gets assigned the same ip addresses everytime.
> Earlier, using DHCP my computer used to join the network with a specific ip everytime (192.168.193.155 for instance). Is it valid if instead of obtaining address repeatedly by DHCP client, I statically assign the same ip, subnet, gateway addresses to my system that were given to me previously? Would that permit me to enter the network?



Let the DHCP assign you the dynamic IP. If you try to force -- might cause conflicts with another machine which has been allocated the IP you want.


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## Zangetsu (Sep 16, 2011)

yrana2002 said:


> Earlier, using DHCP my computer used to join the network with a specific ip everytime (192.168.193.155 for instance). Is it valid if instead of obtaining address repeatedly by DHCP client, I statically assign the same ip, subnet, gateway addresses to my system that were given to me previously? Would that permit me to enter the network?



u can assign a static IP to the machine u use but it should not conflict with any other machine with same ip on network


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## yrana2002 (Sep 16, 2011)

Thanks for the reply.. Actually, i've already tried to statically assign the same ip address, gateway, subnet mask that DHCP server used to provide, however, for some reason, it does not enable me to join the network. 

Any explanation to that?


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## Zangetsu (Sep 16, 2011)

^^as I've told the IP u r assigning currently might be already used by another computer on network.

u can verify it easily..just ping the IP from another computer which is connected to the same network domain....


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## mithun_mrg (Sep 17, 2011)

i think ur service provider has an ip binded to ur mac address so the new dhcp ip will only work


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## jagdish (Sep 17, 2011)

yrana2002,change in Tcp/Ip obtain ip address and dns address automatically,I doubt if you assign a static ip to your computer you will not able to connect to network it is better to leave this  thing to dhcp server to avoid ip conflict.but may i know why you need to assign static ip address.


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## FilledVoid (Sep 17, 2011)

There's a plethora of reasons this could be happening first of all. First Id make sure you have the subnet mask confirmed on your computer to match what you had previously and all other settings like DNS , Gateway etc.  

Secondly as said above if a network admin has a router configured for Static DHCP Binding you can check Cisco's documentation for more on the topic he/she can set it up in such a way that you can't use an IP you configure on your system either. 

Either way its been quite a while since I've fiddled with any routers on a large scale base but may I ask why one earth you would like to make this static ? Is there a particular reason you need the address to be entered in manually?


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## mithun_mrg (Sep 17, 2011)

FilledVoid said:


> why one earth you would like to make this static ? Is there a particular reason you need the address to be entered in manually?



^^ yes absolutely doesn't make sense of an static ip if he is behind a NAT which i think he is


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## yrana2002 (Sep 17, 2011)

Well, basically there seems to be something wrong with my Ethernet card in the sense that, for some reason, its unable to contact DHCP server, as a reason of which no ip gets assigned to my system. 

I tried a usb network card on my same system and it gets the same ip assigned which i used to get previously with my ethernet card. Hence, the effort to assign ip statically to check whether my card could be of any further use.

PS: College network employs MAC address binding so a unique ip address will most likely be reserved for each individual registered system


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## Zangetsu (Sep 17, 2011)

yrana2002 said:


> Well, basically there seems to be something wrong with my Ethernet card in the sense that, for some reason, its unable to contact DHCP server, as a reason of which no ip gets assigned to my system.



if ethernet LAN card has problem then replacing it wud solve your IP issue


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