Desy provides a DHCP Service in different ways for DESY's hole Class-B Network and a Class-C Network called "guest network".

Using DHCP in DESY's Class-B Network "internal":

If you have an registered Hostname associated with an IP-Address and MAC-Address registered by your Segmentadministrator , you can ask him to enable this host also for static DHCP (called manual dhcp or m-dhcp in QIP)
Static DHCP means you will get always the same IP-Address associated with the MAC-Address of your host. The leased time is 7 days.

DESY's Class-C Network called "guest network":

If you have no registered Host at all, you will get an IP-Address dynamically of DESY's Class-C Network 192.76.172.0. The leased time is 1 day. Nobody has to do anything.

For this time the MAC-Address of your host will be registered in QIP (Our IP-Management Tool).
While this time Your Host should be registered by one of the Segmentadministrators You have to release the ip configuration from the dhcp-server. If you shutdown your host the ip configuration should released automatically.
But, if You will be sure and using Windows, you have to do the following on CMD: c:/>ipconfig /release
With linux You can send a DCHP_RELEASE message to the server and destroy dhcpcd cache with /sbin/dhcpcd -k.

What you will get via DHCP

In both cases You will get the following parameters via DHCP:
broadcast-address
subnetmask
default gateway
domain name
domain name server
leased time

For hosts on the internal Network you will also get the hostname and ip-address.

How to check the IP-Configuration of your host

On most Windows Operating Systems you can use
ipconfig -all or ipconfig /all and
on Unix/Linux Systems ifconfig should work.

Example of an WXP Host in the DESY Network:

H:\>ipconfig -all

Windows-IP-Konfiguration

Hostname. . . . . . . . . . . . . : xyz
Primäres DNS-Suffix . . . . . . . : desy.de
Knotentyp . . . . . . . . . . . . : Hybrid
IP-Routing aktiviert. . . . . . . : Nein
WINS-Proxy aktiviert. . . . . . . : Nein
DNS-Suffixsuchliste . . . . . . . : win.desy.de
desy.de
ifh.de

Ethernetadapter DSL-Router DHCP:

Medienstatus. . . . . . . . . . . : Es besteht keine Verbindung
Beschreibung. . . . . . . . . . . : Intel(R) PRO/100 S Desktop Adapter
Physikalische Adresse . . . . . . : aa-bb-cc-dd-ee-ff

Ethernetadapter Intern-131.169.xx.xx:

Verbindungsspezifisches DNS-Suffix: desy.de
Beschreibung. . . . . . . . . . . : Intel(R) PRO/1000 PM Network Connect ion
Physikalische Adresse . . . . . . : aa-bb-cc-dd-ee-ff
DHCP aktiviert. . . . . . . . . . : Ja
Autokonfiguration aktiviert . . . : Ja
IP-Adresse. . . . . . . . . . . . : 131.169.xx.xx
Subnetzmaske. . . . . . . . . . . : 255.255.255.0
Standardgateway . . . . . . . . . : 131.169.xx.xx
DHCP-Server . . . . . . . . . . . : 131.169.40.200
DNS-Server. . . . . . . . . . . . : 131.169.40.200
131.169.194.200
Primärer WINS-Server. . . . . . . : 131.169.69.194
Lease erhalten. . . . . . . . . . : Sonntag, 29. Juli 2007 18:11:48
Lease läuft ab. . . . . . . . . . : Sonntag, 5. August 2007 18:11:48

H:\>

If your host is connected on the Guest Network the IP-Address looks like 192.76.172.x.