ime this will become tedious and can become the likely source for operational roaming problems. Another alternative is to have common a GPRS root nameserver. Every change in domain or DNS information is updated at the master GPRS root nameserver and the changed information is immediately active. Because the GPRS root nameserver is critical for operation, it will normally be repli- cated at several locations in the inter-PLMN backbone network as a matter of prudent operation. GPRS root nameservers should contain necessary information to reach the individual operator DNS servers. Root server secu- rity is crucial. For example, they may only provide zone transfer to other GPRS root nameservers. Dynamic Host Configuration Protocol (DHCP) DHCP is also based on a client-server architecture, whereby the DHCP client (such as a desktop computer) contacts a DHCP server for configura- tion parameters. The DHCP server is typically centrally located and oper- ated by the network administrator. Because a network administrator runs the server, DHCP clients can be configured reliably and dynamically with parameters appropriate to the current network architecture. The most important configuration parameter carried by DHCP is the IP address. A computer must be initially assigned a specific IP address that is appropriate to the network to which the computer is attached and that is not assigned to any other computer on that network. If a computer moves to a new network (such as a GPRS or other mobile network), it must be assigned a new IP address for that new network. DHCP can be used to automatically manage these assignments. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hil Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Function of GPRS Elements Function of GPRS Elements DHCP carries other important configuration parameters such as the subnet mask, default router (the GGSN address), and Domain Name Sys- tem 