This section explains the problems that may cause the symptoms listed above, and suggests ways to solve the problems.
1. Incorrect parameters supplied to hosts_to_named.
Check the domain data files to be sure they contain records for the hosts in your domain. If localhostis the only host listed, you may have supplied incorrect domain names or network numbers to hosts_to_named.
2. Syntax error in the named.conf file or a data file.
• syslogd
Syntax error messages are logged indicating the file name and line number.
• Name server debugging output
Start the name server at debug level 1. Look for syntax error messages in /var/tmp/named.runindicating the file name and line number.
• ping hostname
If ping indicates that the host is unknown and the local name server should be authoritative for that name, the syntax error is probably in the file that maps host names to Internet addresses, db.domain.
3. Missing cache information about the root servers. Without information about the root servers, names outside of the local domain cannot be looked up because the local server relies on the root servers to direct it to servers for other domains.
• syslogd
Queries for names outside of the local domain cause syslogd to log the following message: No root name servers for class 1. (Class 1 is the IN class.)
• nslookup
nslookupmay fail to look up the local host’s name on startup and give a servfail message. To verify root server information, execute the following:
$ nslookup > set type=NS > .
This asks for the NS records for the root. If no records for root servers are present, it returns Can't find ".": Server failed.
• ping hostname
Names in the local domain are found, while names in remote domains are not found. — Name server debugging output
Set debugging to level 1. Use ping on a host name not in the local domain. The debugging output in /var/tmp/named.run contains the following: No root name servers for class 1. (Class 1 is the IN class.)
— Dumping the name server database
No root server data appears in the “Hints” section at the end of the file
/var/tmp/named_dump.db.
4. Syntax errors in /etc/resolv.conf (for remote server configuration only). This assumes that the server on the remote host is configured properly. Errors in /etc/resolv.conf are silently ignored by the resolver code.
• ping IP_addressor ping hostname
Only names in the NIS database or /etc/hosts file can be looked up. ping the remote server’s address to verify connectivity.
• Name server debugging output
Turn on debugging on the remote server. Verify that it is receiving queries from the local host. If queries are not being received, examine the name server entries in /etc/resolv.confand verify network connectivity to the remote server. 5. Network connectivity problems may cause certain lookups to fail. See the Installing and
Administering LAN/9000 Software manual for information on troubleshooting network
connectivity.
• Name server debugging output
Turn on debug level 1. Use ping on the host name. Examine the name server debugging output in /var/tmp/named.run for lines like this:
req: found `cucard.med.columbia.edu’ as `columbia.edu’ resend(addr=1 n=0) -> 128.59.32.1 6 (53) nsid=18 id=1 0ms resend(addr=2 n=0) -> 128.59.40.130 6 (53) nsid=18 id=1 0ms resend(addr=3 n=0) -> 128.103.1.1 6 (53) nsid=18 id=1 764ms
In this case the name server tries to contact the columbia.edu name servers but does not get a response. Use ping on the addresses the server is trying to contact to verify network connectivity.
If the addresses being tried are the root name servers, either the host does not have connectivity to these machines, or the root server addresses are wrong.
• nslookup
nslookuptimes out while trying to look up the name.
• ping hostname
6. Slave master is unable to load from another master. This may be caused by a configuration error or problems with network connectivity. Verify that the domain being loaded and the address of the remote server are correct in the configuration file.
• syslogd
An error message is logged indicating the master server for the secondary zone is unreachable.
• Name server debugging output
Start the slave server at debugging level 2 or 3. Watch for error messages in the debug output. These could show that the other server is unreachable, the other server is not authoritative for the domain, or the local SOA serial number is higher than the remote SOAserial number for this zone.
• ping IP_address
Verify connectivity to the server the secondary is trying to load from. If the host is temporarily unreachable, the slave server will load when it is reachable.
• nslookup
Use nslookup and set the name server to the master the secondary is trying to load from.
$ nslookup
> server server_name or IP_address > ls domain
The ls command initiates a zone transfer. If the error message is No response from server, then no server is running on the remote host. If the ls command succeeds, the secondary should be able to load the data from this server.
7. Incorrect subdomain delegation may be caused by missing or incorrect NS or A records in the parent server for the subdomain.
• nslookup
Use nslookup to query the parent server for delegation information. Execute the following:
$ nslookup
> server parent_server_name or IP_address > set type=ns
> subdomain_name
This must show you the NS and A records for the subdomain servers, as seen in the following example. In the example, the subdomain is delegated correctly.
hershey.div.inc.com:rootk> nslookup Default Name Server: hershey.div.inc.com Addresses: 15.19.14.100, 15.19.15.100
hersheyis the default name server for this host.
> server eduardo.doc.inc.com.
Default Name Server: eduardo.doc.inc.com Address: 15.19.11.2
Set the default name server to be this subdomain’s parent server, eduardo.
> set type=ns > div.inc.com
Name Server: eduardo.doc.inc.com Address: 15.19.11.2
Non-authoritative answer:
div.inc.com nameserver = walleye.div.inc.com div.inc.com nameserver = friday.div.inc.com
Name server records for div.inc.com, the delegated subdomain. Authoritative answers can be found from:
walleye.div.inc.com inet address = 15.19.13.197 friday.div.inc.com inet address = 15.19.10.74
Address records for the name servers for div.inc.com.
• Dumping the name server database
Because the name server caches information, a database dump can be searched for the NSand A records for the subdomain. If no NS or A records exist, the parent server for the subdomain or the root servers are not reachable. If NS and A records exist, check their correctness. Then try pinging the addresses of the name servers to see if they are reachable.
• Name server debugging output
Turn on debugging to level 1 and try to look up a name in the domain. Verify the debug output for name server retransmissions. This indicates which servers are not responding. Verify that the servers and their addresses are correct, if possible.
8. The local domain is not set. The local domain is used to complete names that do not end with a dot. To set the local domain, either set the host name (hostname) of the local system to a domain name (without a trailing dot), or add a domain entry to /etc/resolv.conf.
• nslookup
nslookupgives a warning that the local domain is not set.
• Name server debugging output
The debug output at level 1 shows names being looked up that are not domain names.
• ping hostname
hostnameis found only when it is a completely specified domain name (with or without
a trailing dot).
9. The /etc/nsswitch.conf file, if it exists, is not configured correctly. If you want to query BIND before querying NIS or the /etc/hosts file, make sure dns is listed first on the hostsline. See the HP-UX Internet Services Administrator’s Guide for information on how to configure the name service switch.
10. The /etc/hosts file or NIS contains incorrect data. The name service switch
(/etc/nsswitch.conf) allows host name lookups in /etc/hosts or NIS, and one of those databases contains incorrect data. For information on configuring the /etc/hosts file, see the HP-UX Internet Services Administrator’s Guide for information on how to edit the /etc/hosts file. For information on NIS, see NIS Administrator's Guide.