NCD terminals can use both DNS (Domain Name System) and IEN 116 name services.
Making Sure a Name Service is Running on the Local Network
To make sure DNS is available on the name server host:
# grep named /etc/rc*/etc/rc.local: if [-f /usr/etc/in.named -1 -f /etc/named.boot]; then
in.named; echo -n ' named') > /dev/console
To make sure IEN 116 name service is available on the name server host:
#
grep tnamed /etc/inetd.confname dgram udp wait root /user/etc/in.tnamed in.tnamed
Making Sure the Terminal Uses the Name Service
You should always place name service parameters at the beginning of a remote configuration file, before any parameters that use hostnames. In addition, insert an apply command after the name service parameters to make sure the name service is in effect for subsequent parameters that use hostnames.
Selecting the Name Service Protocol
Set the tcpip-name-server-protocol parameter to the name service protocol you are using (Setup -> Change Setup Parameters -> TCP/IP Name Service -> Name Server Protocol).This parameter is saved in NVRAM and takes effect immediately if set interactively.
If you use BOOTP/DHCP and specify name servers for this terminal in the bootptab file, those name servers are placed in the table automatically. This parameter is saved in NVRAM.
Table 5-6 tcpip-name-servers Parameter
Table Entry
Possible Values
Result
server
default
0.0.0.0
IP address
The name server with this IP address is used to map host IP addresses to symbolic names.
tcpip-name-servers = {
{ 192.43.150.001 }
{ 192.43.150.005 }
}
If you are using DNS and set this parameter, you do not have to specify a fully qualified domain name when specifying hostnames. Set the tcpip-dns-default-domain parameter to the default domain suffix to be appended to hostnames in searches (Setup -> Change Setup Parameters -> TCP/IP Name Service -> DNS Default Domain). The suffix is not appended to fully qualified names (names that contain all the components of the domain name).
tcpip-dns-default-domain = ncd.com
Table 5-7 tcpip-dns-default-domain Parameter
Possible Values |
Result |
---|---|
default | nil |
nil | No suffix is applied to hostnames in name service searches. |
domain suffix | The suffix applied to hostnames in name service searches. |
Translations are automatically placed in the local name cache. If your site does not run a name service, you can place translations into the table manually.
The terminal maintains the local name cache in the tcpip-name-local-cache parameter (Setup -> Change Setup Parameters -> TCP/IP Name Service -> Local Name Cache). Table 5-8 lists the entries in each row of the table.
Table 5-8 tcpip-name-local-cache Table Entries
To customize the local name cache, you can change the following parameters; however, the defaults work well for most sites.
Setting the Name Cache Entry Lifetime
The tcpip-name-cache-max-lifetime parameter controls the maximum amount of time that an entry in the cache is used before it is deleted automatically (Setup -> Change Setup Parameters -> TCP/IP Name Service -> Name Cache Max Lifetime).
Table 5-9 tcpip-name-cache-max-lifetime Parameter
Possible Values |
Result |
---|---|
default | 1800 |
integer | The maximum lifetime (in seconds) of the name cache. Range: 0 - 4294967295. |
The tcpip-name-cache-max-size parameter sets the maximum number of entries allowed in the name cache (Setup -> Change Setup Parameters -> TCP/IP Name Service -> Name Cache Max Size). When the maximum size is reached, the oldest entry is discarded when a new entry is added. You may want to restrict the size of the cache to save memory for other uses.
Table 5-10 tcpip-name-cache-max-size Parameter
Possible Values
Result
default
32
integer
The maximum number of entries in the name cache. Range: 0 - 4294967295 or until all free memory is consumed.
Setting Name Service Timeouts
The tcpip-name-server-retransmission-timeout parameter determines how long the terminal waits before sending a retransmission if the name server does not respond (Setup -> Change Setup Parameters -> TCP/IP Name Service -> Name Server Retransmission Timeout).
Table 5-11 tcpip-name-server-retransmission-timeout
Possible Values
Result
default
2
integer
How long to wait (in seconds) before retransmitting a name service request. Range: 1 - 4294967295.
The tcpip-name-server-transaction-timeout parameter determines how long the terminal waits for a response from the name server before failure is declared (Setup -> Change Setup Parameters -> TCP/IP Name Service -> Name Server Transaction Timeout). The value of this parameter should be larger than the retransmission timeout.
Table 5-12 tcpip-name-server-transaction-timeout
Possible Values
Result
default
10
integer
How long (in seconds) to attempt a name service request before declaring a failure condition. Range: 1 - 4294967295.
Discovering the Terminal's Hostname when Booting (Reverse Name Request)
The unit-query-for-name-at-boot parameter controls whether, at boot time, the terminal sends a reverse name request to the DNS name servers to find the terminal's host name (Setup -> Change Setup Parameters -> Unit -> Query for Unit Name at Boot).