DHCP entries with blank names

Does anyone know why some DHCP entries show blank names?  IP, Lease expiration, MAC address, etc.  Just missing a name.  
Would that be some sort of an appliance/hw that without a hostname assigned?
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zvitamConnect With a Mentor ConsultantCommented:
You can also try to detect the vendor of the device by the 6 most significant digits in MAC address see the Following List
Saurav SinghConnect With a Mentor Senior IT Security AnalystCommented:
DHCP is a very simple system which operates at a low level in the network. The client simply broadcasts a request on the network and the DHCP server replies with an offer. The blank leases are devices that are not providing DHCP with a host name.  Take a look at those devices (you can find them by MAC looking up the MAC tables in your switches, if they are managed switches), then follow the cable to the device.  If these are wireless devices, you will need to put some security into the edge. It could be helpful In the environment that use both thin clients and VOIP phones. Both will show up in DHCP without host names and consiquently do not show up in DNS
Tiras25Author Commented:
Thanks Saurav.  Very helpful.  Interestingly enough all my VoIP phones do show hostnames.  Which is a make/model/mac.  But some other devices don't.  They are most likely some switches etc.  Thought they should have some default hostnames as well, but maybe they not broadcasting those names though.

Do I have to worry about those devices that don't broadcast their hostnames?
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Are there any mobile phones connected to your network by WiFi? if so, it might be the answer...
Tiras25Author Commented:
Yes, hundreds, and every mobile phone displays the name.  Either the default or modified name by user.
nociConnect With a Mentor Software EngineerCommented:
You don't need to wory, sometimes hostnames are easier to find equipment back then just MAC address.
You can also configure a hostname through DHCP..., just give them a hostname & reservation based om MAC....
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