DHCPREQUEST with hostname

Question

Hi,We see some strange behaviour of the Macs in our network. We want it to be default, that the Macs send their Hostnames when doing a DHCPREQUEST.For example, here (10.6.8) it does:Jul 14 09:19:29 gw01 dhcpd: DHCPREQUEST for 192.168.3.24 from e8:06:88:bc:f1:0a (Xxxx-MacBook) via eth0And here (also 10.6.8) on another Mac it doesn&#x27;t:Jul 14 14:47:45 gw01 dhcpd: DHCPREQUEST for 192.168.2.41 from c8:2a:14:30:2a:7b via eth0So there needs to be an option or flag or whatever where I can tell my mac, to send its hostname!Does anyone know what to do to get the macs send their hostname when they do a DHCPREQUEST?

lfronius · Accepted Answer

I can not believe that there is no solution for this problem.Something must have changed, cause all newer macs we have here don&#x27;t send their hostname while doing a DHCPREQUEST.I don&#x27;t think I am the only one with this problem...Well, maybe I have more luck this time, since my post should be up at the latest posts again now 😉

kirchmeyer · Answer

I&#x27;ve been looking and also have not found the answer.

qris1 · Answer

I discovered that Macs sometimes send their hostname in the request, and sometimes do not. In particular I found that if the computer name (Control Panel &gt; Sharing -&gt; Computer name) contains a space, then NO hostname will be sent (under OS X 10.6). If it does NOT contain a space, then it WILL be sent.I compared the DHCP requests using tcpdump, with and without a space in the computer name.With the computer name &#x60;chris-macbook-space&#x60;:    11:13:41.939462 IP (tos 0x0, ttl 255, id 36007, offset 0, flags [none], proto UDP (17), length 328)    0.0.0.0.68 &gt; 255.255.255.255.67: BOOTP/DHCP, Request from 00:17:f2:xx:xx:xx, length 300, xid 0x9b57c74c, secs 1, Flags [none]            Client-Ethernet-Address 00:17:f2:xx:xx:xx            Vendor-rfc1048 Extensions              Magic Cookie 0x63825363              DHCP-Message Option 53, length 1: Discover              Parameter-Request Option 55, length 10:                 Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name                Option 119, LDAP, Option 252, Netbios-Name-Server                Netbios-Node, Netbios-Scope              MSZ Option 57, length 2: 1500              Client-ID Option 61, length 7: ether 00:17:f2:xx:xx:xx              Lease-Time Option 51, length 4: 7776000              Hostname Option 12, length 19: "chris-macbook-space"With the computer name &#x60;chris-macbook space&#x60;:    11:07:13.077664 IP (tos 0x0, ttl 255, id 36003, offset 0, flags [none], proto UDP (17), length 328)    0.0.0.0.68 &gt; 255.255.255.255.67: BOOTP/DHCP, Request from 00:17:f2:xx:xx:xx, length 300, xid 0x432cbbda, secs 2, Flags [none]            Client-Ethernet-Address 00:17:f2:xx:xx:xx            Vendor-rfc1048 Extensions              Magic Cookie 0x63825363              DHCP-Message Option 53, length 1: Discover              Parameter-Request Option 55, length 10:                 Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name                Option 119, LDAP, Option 252, Netbios-Name-Server                Netbios-Node, Netbios-Scope              MSZ Option 57, length 2: 1500              Client-ID Option 61, length 7: ether 00:17:f2:xx:xx:xx              Lease-Time Option 51, length 4: 7776000Note the missing &#x60;Hostname Option 12, length 19: "chris-macbook-space"&#x60; in the latter case.So you could try removing spaces and any other special characters from the computer name, to see if that enables it to be resolved on the network.