org.apache.hadoop.net

Interface DomainNameResolver

All Known Implementing Classes:

DNSDomainNameResolver

public interface DomainNameResolver

This interface provides methods for the failover proxy to get IP addresses of the associated servers (NameNodes, RBF routers etc). Implementations will use their own service discovery mechanism, DNS, Zookeeper etc

Method Summary

Modifier and Type	Method and Description
InetAddress[]	getAllByDomainName(String domainName) Takes one domain name and returns its IP addresses based on the actual service discovery methods.
String[]	getAllResolvedHostnameByDomainName(String domainName, boolean useFQDN) This function combines getAllByDomainName and getHostnameByIP, for a single domain name, it will first do a forward lookup to get all of IP addresses, then for each IP address, it will do a reverse lookup to get the fqdn.
String	getHostnameByIP(InetAddress address) Reverse lookup an IP address and get the fully qualified domain name(fqdn).

Method Detail

getAllByDomainName

InetAddress[] getAllByDomainName(String domainName)
                          throws UnknownHostException

Takes one domain name and returns its IP addresses based on the actual service discovery methods.

Parameters:

domainName -

Returns:

all IP addresses

Throws:

UnknownHostException

getHostnameByIP

String getHostnameByIP(InetAddress address)

Reverse lookup an IP address and get the fully qualified domain name(fqdn).

Parameters:

address -

Returns:

fully qualified domain name

getAllResolvedHostnameByDomainName

String[] getAllResolvedHostnameByDomainName(String domainName,
                                            boolean useFQDN)
                                     throws UnknownHostException

This function combines getAllByDomainName and getHostnameByIP, for a single domain name, it will first do a forward lookup to get all of IP addresses, then for each IP address, it will do a reverse lookup to get the fqdn. This function is necessary in secure environment since Kerberos uses fqdn in the service principal instead of IP.

Parameters:

domainName -

Returns:

all fully qualified domain names belonging to the IPs resolved from the input domainName

Throws:

UnknownHostException