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How to Manage DNS Registrations for Your Subnet

If you're responsible for network connections in your department or building, you need to register all the network devices into DNS as per university policy 5.7, Network Registry. For more information, see How to Comply with Network Registration Policy.

Your first step should be to register as a Netadmin.

Register as a Netadmin with the Cornell Hostmaster

  1. Send an email to hostmaster@cornell.edu. Include:
  • The IP address range(s) of your subnet(s), for example 128.253.230.64  128.253.230.255.
  • The name(s) of your domain(s), for example dept.cornell.edu.
  • The names, NetIDs, and e-mail addresses of each person who has responsibility for these networks, including yourself.

After registering as a Netadmin, you will be able to:

  • Update info about your subnets, domains, and hosts in Cornell's DNS database.
  • Receive announcements of changes that affect your subnet(s), and announcements of new services such as the DNS database and DHCP support.
  • Create an escalation path for the Network Operations Center to use if a serious problem needs to be reported at night or on a weekend.

Choosing Between DHCP and Manually Configuring DNS

DHCP

DHCP (Dynamic Host Configuration Protocol) is designed to allow you to administer a large IP network more efficiently. A central network server distributes configuration information such as DNS servers, subnet mask, gateways and most importantly, IP address, to individual machines.

CIT offers a campus-wide DHCP service.

DHCP reduces paperwork while increasing your control over your subnet. DHCP can:

  • Automate some subnet record-keeping, such as tracking which IP numbers are in use, and who is using them.
  • Document visitors on the LAN.
  • Centralize network configuration.
  • Facilitate major changes in the IP protocol configuration. This means changes such as campus DNS or the local subnet's gateway can be made without an administrator visiting each machine.
  • Enforce IP address distribution restrictions for your subnet.
  • Make it easier for users to move between home and office.

For more information, see Plan and Implement DHCP on Your Subnet.

Manually Enter DNS Registration

Use one of two methods:

  1. The host list web page at http://dnsdb.cit.cornell.edu/dnsdb-cgi/host.pl for updating one machine at a time.
  2. The batch load interface at http://dnsdb.cit.cornell.edu/dnsdb-cgi/batch.pl for updating multiple machines at once:
    • To create a record: addhost hostnam ipaddr
    • To record the MAC address: addmac ipaddr macaddr
    • To record the NetID: chgowner hostname netid

Note: The last two commands are necessary to comply with the Network Registry Policy. For more information see How to Comply with Network Registry Policy.