Netstat RESCache/-q report

Displays system-wide resolver cache information. This information is not specific to the TCP/IP stack whose name was specified on the TCp/-p target parameter or to the default TCP/IP stack. Statistical information, such as number of record entries or number of cache queries, can be retrieved, or detailed information about some or all of the cache entries can be retrieved. Resolver caching is configured using resolver configuration statements in the resolver setup file. For more information about resolver caching, see details about resolver caching in z/OS Communications Server: IP Configuration Guide.

TSO syntax


>>---NETSTAT RESCache--| Modifier |--| Target |--| Output |--| (Filter |---><

Modifier


   .-SUMmary--------------.   
>>-+----------------------+------------------------------------><
   +-DETAIL--+----------+-+   
   |         '-NEGative-' |   
   '-SUMmary--+-----+-----'   
              '-DNS-'

DETAIL

Display detailed information for all unexpired entries that are currently in the resolver cache. It includes the following information:

Host-name-to-IP-address entries from resolver forward lookups.
IP-address-to-host-name entries from resolver reverse lookups.
Negative entries that are included in both forward and reverse lookup tables.

NEGative: Display detailed information for all negative cache entries in the resolver cache.

SUMmary

Display general system statistics for resolver cache operations. This is the default report for the RESCACHE report option.

DNS: Display general system statistics for resolver cache operations, plus individual statistics for each DNS name server that has provided information currently stored in the cache.

Target

Provide the report for a specific TCP/IP address space by using the TCp tcpname option. See The Netstat command target for more information about the TCp parameter.

Output

The default output option displays the output on the user terminal. For other options, see Netstat command output.

Filter


>>-+-DNSAddr--dnsaddr---+--------------------------------------><
   +-HOSTName--hostname-+   
   '-IPAddr--ipaddr-----'

z/OS UNIX syntax


>>---netstat -q--| Modifier |--| Target |--| Output |--| Filter |---><

Modifier


   .-SUMmary--------------.   
>>-+----------------------+------------------------------------><
   +-DETAIL--+----------+-+   
   |         '-NEGative-' |   
   '-SUMmary--+-----+-----'   
              '-DNS-'

DETAIL

Display detailed information for all unexpired entries that are currently in the resolver cache. See the following entries:

Host-name-to-IP-address entries from resolver forward lookups.
IP-address-to-host-name entries from resolver reverse lookups.
Negative entries that are included in both forward and reverse lookup tables.

NEGative: Display detailed information for all negative cache entries that are in the resolver cache.

SUMmary

Display general system statistics for resolver cache operations. This is the default report for the RESCACHE report option.

DNS: Display general system statistics for resolver cache operations, plus individual statistics for each DNS name server that has provided information currently stored in the cache.

Target

Provide the report for a specific TCP/IP address space by using the TCp tcpname option. See The Netstat command target for more information about the -p parameter.

Ouptut

The default output option displays the output on the user terminal. For other options, see Netstat command output.

Filter


>>-+- -H--hostname-+-------------------------------------------><
   +- -I--ipaddr---+   
   '- -Q--dnsaddr--'

Filter description

DNSAddr/-Q dnsaddr

Filter the output of the RESCache/-q report using the specified DNS IP address dnsaddr. You can enter one filter value at a time. The specified IPv4 dnsaddr value can be up to 15 characters in length; the specified IPv6 dnsaddr value can be up to 45 characters in length.

Restriction: The filter value does not support wildcard characters.

HOSTName/-H hostname

Filter the output of the RESCache/-q report using the specified host name value hostname. You can enter one filter value at a time. The specified value can be up to 255 characters in length.

Restriction: The HOSTName/-H filter applies only to the IPAddress to HostName translation portion of the report

The filter value for HOSTName/-H can be a complete string or a partial string that can use wildcard characters. A wildcard character can be an asterisk (*), which matches a null string or any character or character string, in the same position. A wildcard character can also be a question mark (?), which matches any single character in the same position. For example, the string searchee matches with the search value *ar?he*, but the string searhee does not match with the search value *ar?he*.

In addition to the asterisk (*) and question mark (?) wildcard characters, the HOSTName/-H filter also supports implicit wildcards. Implicit wildcards are handled similarly to the way resolver queries handle host names. For example, if you specify the filter value host21, the query returns resolver cache information for the following cache entries:

host21
host21.ibm.com
host21.raleigh.ibm.com
Any entry that has host21 as the value that precedes the first period in the fully-qualified domain name

However, if you specify the filter value host21.,the query matches only the entry host21.

Tip: The filter value host21 is equal to host21.* but host21 is not equal to host21* because host21* also matches cache entries such as host211.ibm.com and host2134.ibm.com.

When you use the z/OS UNIX netstat/onetstat command in a z/OS UNIX shell environment, using a z/OS UNIX MVS™ special character in a character string might cause an unpredictable result. If you want to use a z/OS UNIX MVS special character in a character string, surround the character string with single quotation marks (') quotation marks ("). For example, to use an asterisk (*) in the host name, cat.* for the -H filter, issue the command as: netstat -q -H 'cat.*' or netstat -q -H "cat.*".

IPAddr/-I ipaddr

Filter the output of the RESCache/-q report using the specified IP address ipaddr. You can enter one filter value at a time. The specified IPv4 ipaddr value can be up to 15 characters in length; the specified IPv6 ipaddr value can be up to 45 characters in length.

Restrictions:

The filter value does not support wildcard characters.
The IPAddr/-I filter applies only to the IPAddress to HostName translation portion of the report.

Use the RESCache/-q filters only when you use the DETAIL modifier. Specifying a filter with the SUMMARY modifier does not affect the report output.

Command syntax examples

From TSO environment

 NETSTAT RESCACHE SUMMARY                                                               
   Display general system statistics for resolver cache operations                      
 NETSTAT RESCACHE SUMMARY DNS                                                           
   Display general system statistics for resolver cache operations, plus individual     
   statistics for each DNS name server that has provided information currently   
   stored in the cache.                                                                 
 NETSTAT RESCACHE DETAIL                                                                
   Display detailed information for all unexpired entries that are currently 
   in the resolver cache.
 NETSTAT RESCACHE DETAIL (DNSADDR 10.7.7.7                                              
   Display detailed information for all unexpired entries that are currently 
   in the resolver cache that were provided by the DNS name server at IP address 10.7.7.7
 NETSTAT RESCACHE DETAIL (HOSTName hostname.domain                                      
   Display detailed information for all HostName to IPAddress resolution cache 
   entries currently in the resolver cache that were acquired using host name 
   hostname.domain as the target resource for the resolver query.                                       
 NETSTAT RESCACHE DETAIL (HOSTName hostname.*                                           
   Display detailed information for all HostName to IPAddress resolution cache 
   entries currently in the resolver cache that were acquired using a host name matching 
   the hostname.* pattern string as the target resource for the resolver query.             
 NETSTAT RESCACHE DETAIL (IPAddr 10.9.9.9                                               
   Display detailed information for all IPAddress to HostName resolution 
   cache entries currently in the resolver cache that were acquired using IP address 
   10.9.9.9 as the target resource for the resolver query.                                       
 NETSTAT RESCACHE DETAIL NEGATIVE                                                       
   Display detailed information for all negative cache entries in the resolver cache

From UNIX shell environment

 netstat -q SUMMARY
 netstat -q SUMMARY DNS
 netstat -q DETAIL
 netstat -q DETAIL -Q 10.7.7.7
 netstat -q DETAIL -H hostname.domain
 netstat -q DETAIL -H 'hostname.*'
 netstat -q DETAIL -I 10.9.9.9
 netstat -q DETAIL NEGATIVE

Report examples

The following examples are generated by using the TSO NETSTAT command. Using the z/OS UNIX netstat command displays the data in the same format as the TSO NETSTAT command.

NETSTAT RESCACHE or NETSTAT RESCACHE SUMMARY

MVS TCP/IP NETSTAT CS V2R1       TCPIP Name: TCPCS           15:12:31
Storage Usage:
  Maximum: 10M
    Current: 203K   MaxUsed: 1M

Cache Usage:
  Total Number of entries: 64
    Non-NX entries: 44
      A: 20         AAAA: 13         PTR: 11
    NX entries: 20
      A: 9          AAAA: 2          PTR: 9
  Queries: 112                  Hits: 34
  SuccessRatio: 30%

NETSTAT RESCACHE SUMMARY DNS

MVS TCP/IP NETSTAT CS V2R1       TCPIP Name: TCPCS           15:12:45
Storage Usage:
  Maximum: 10M
    Current: 203K   MaxUsed: 1M

Cache Usage:
  Total Number of entries: 64
    Non-NX entries: 44
      A: 20         AAAA: 13         PTR: 11
    NX entries: 20
      A: 9          AAAA: 2          PTR: 9
  Queries: 112                  Hits: 34
  SuccessRatio: 30%

DNS address: 19.47.135.295
  Total Number of entries: 54
    Non-NX entries: 39
      A: 18         AAAA: 11         PTR: 10
    NX entries: 15
      A: 7          AAAA: 2          PTR: 6
  References: 77                   Hits: 21

DNS address: 19.52.206.22
  Total Number of entries: 10
    Non-NX entries: 5
      A: 2          AAAA: 2          PTR: 1
    NX entries: 5
      A: 2          AAAA: 0          PTR: 3
  References: 43                   Hits: 13

NETSTAT RESCACHE DETAIL

MVS TCP/IP NETSTAT CS V2R1       TCPIP Name: TCPCS           15:12:51
HostName to IPAddress translation
---------------------------------
HostName: HOSTNAME1
  DNS IPAddress: 19.47.135.295
  DNS Record Type: T_A
  Canonical Name: ***NA***
  Cache Time: 10/27/2011 18:44:43
  Expired Time: 10/27/2011 19:44:33
  Hits: 0
  IPAddress: ***NA***

HostName: HOSTNAME4.TCP.RALEIGH.IBM.COM
  DNS IPAddress: 19.47.135.295
  DNS Record Type: T_A
  Canonical Name: hostname4.tcp.raleigh.ibm.com
  Cache Time: 10/27/2011 18:36:51
  Expired Time: 10/28/2011 14:25:16
  Hits: 0
  IPAddress: 29.72.105.195
             29.72.105.196
             29.72.105.197

HostName: HOSTNAME1.TCP.RALEIGH.IBM.COM
  DNS IPAddress: 19.47.135.295
  DNS Record Type: T_A
  Canonical Name: ***NA***
  Cache Time: 10/27/2011 18:44:38
  Expired Time: 10/27/2011 19:44:28
  Hits: 0
  IPAddress: ***NA***

HostName: HOSTNAME5.TCP.RALEIGH.IBM.COM
  DNS IPAddress: 19.47.135.295
  DNS Record Type: T_A
  Canonical Name: hostname5.pok.ibm.com
  Cache Time: 10/27/2011 18:43:22
  Expired Time: 10/27/2011 20:09:38
  Hits: 0
  IPAddress: 29.236.231.69

HostName: WWW.NEWSPAPER.COM
  DNS IPAddress: 19.52.206.22
  DNS Record Type: T_A
  Canonical Name: newspaper.com
  Cache Time: 10/27/2011 19:05:29
  Expired Time: 10/27/2011 20:05:29
  Hits: 0
  IPAddress: 125.152.8.134

HostName: HOSTNAME5.TCP.RALEIGH.IBM.COM
  DNS IPAddress: 19.52.206.22
  DNS Record Type: T_A
  Canonical Name: hostname55.pok.ibm.com
  Cache Time: 10/27/2011 19:06:36
  Expired Time: 10/27/2011 20:09:37
  Hits: 1
  IPAddress: 29.236.231.69

HostName: WWW.STATE1.GOV
  DNS IPAddress: 19.52.206.22
  DNS Record Type: T_AAAA
  Canonical Name: state1.gov
  Cache Time: 10/27/2011 19:09:24
  Expired Time: 10/27/2011 19:19:24
  Hits: 0
  IPAddress: 144::227:12:34:76

HostName: WWW.COLLEGE1.EDU
  DNS IPAddress: 19.52.206.22
  DNS Record Type: T_AAAA
  Canonical Name: www.college1.edu
  Cache Time: 10/27/2011 19:08:45
  Expired Time: 10/27/2011 19:18:45
  Hits: 0
  IPAddress: 1004::251:133:180:120
             1004::251:133:180:121

HostName: WWW.COMPANY.COM
  DNS IPAddress: 19.52.206.22
  DNS Record Type: T_AAAA
  Canonical Name: ***NA***
  Cache Time: 10/27/2011 19:11:20
  Expired Time: 10/27/2011 19:28:00
  Hits: 2
  IPAddress: ***NA***

IPAddress to HostName translation
---------------------------------
IPAddress: 930::159:84:218:223
  DNS IPAddress: 19.47.135.295
  DNS Record Type: T_PTR
  Cache Time: 10/27/2011 19:07:43
  Expired Time: 10/27/2011 19:17:43
  Hits: 1
  HostName: hostipv6-223.218.84.150.company.com

IPAddress: 152.12.39.164
  DNS IPAddress: 19.52.206.22
  DNS Record Type: T_PTR
  Cache Time: 10/27/2011 19:05:59
  Expired Time: 10/27/2011 20:05:59
  Hits: 1
  HostName: ***NA***

IPAddress: 159.84.218.223
  DNS IPAddress: 19.52.206.22
  DNS Record Type: T_PTR
  Cache Time: 10/27/2011 19:05:43
  Expired Time: 10/27/2011 19:15:43
  Hits: 1
  HostName: hostvalue-223.218.84.159.company.com

IPAddress: 152.152.31.134
  DNS IPAddress: 19.52.206.22
  DNS Record Type: T_PTR
  Cache Time: 10/27/2011 19:05:59
  Expired Time: 10/27/2011 20:05:59
  Hits: 1
  HostName: namemh.media.com

Report field descriptions

SUMMARY or SUMMARY DNS reports

Storage Usage

Displays information about the overall storage usage for resolver caching. This storage represents 64-bit private storage in the resolver address space.

Maximum

Displays the maximum amount of storage that the resolver can allocate to manage cache records. This value was defined using the CACHESIZE resolver setup statement. This value can be displayed as a number followed by the letter M.

Current

Displays the current amount of storage that the resolver has allocated to manage cache records. This value can be displayed in the following forms:

If the value is less than 1 MB, then it is displayed as a number followed by the letter K.
If the value is 1 MB or greater, it is displayed as a number followed by the letter M.

MaxUsed

Displays the greatest amount of storage that the resolver has ever allocated for managing cache records. This value can be displayed in the following forms:

If the value is less than 1 MB, then it is displayed as a number followed by the letter K.
If the value is 1 MB or greater, it is displayed as a number followed by the letter M.

Cache Usage

Displays information about the number and the makeup of the records that are currently in the resolver cache. This value includes both NX (negative cache entries) and non-NX entries.

Total number of entries

Displays the total number of A, AAAA, and PTR cache entries that are currently in the resolver cache. This value includes both NX (negative cache entries) and non-NX entries.

Non-NX entries

Displays the total number of A, AAAA, and PTR cache entries that represent successful name or address resolution attempts, that are in the resolver cache. An individual cache entry represents one of the following case:

A host-name-to-IPv4-address resolver query to a specific name server, for which the name server returned at least one IPv4 address.
A host-name-to-IPv6-address resolver query to a specific name server, for which the name server returned at least one IPv6 address.
An IP-address-to-host-name resolver query to a specific name server, for which the name server returned a host name.

A: Displays the total number of A cache entries that are currently in the resolver cache that were created as a result of a successful resolution attempt. An individual A cache entry contains the results of one host-name-to-IPv4-address resolver query to a specific name server, even if multiple IPv4 addresses were returned by the name server for the target host name.
AAAA: Displays the total number of AAAA cache entries that are currently in the resolver cache that were created as a result of a successful resolution attempt. An individual AAAA cache entry contains the results of one host-name-to-IPv6-address resolver query to a specific name server, even if multiple IPv6 addresses were returned by the name server for the target host name.
PTR: Displays the total number of PTR cache entries that are currently in the resolver cache that were created as a result of a successful resolution attempt. An individual PTR cache entry contains the results of one IP-address-to-host-name resolver query to a specific name server. The target IP address can be either an IPv4 address or an IPv6 address.

NX entries

Displays the total number of A, AAAA, and PTR negative cache entries that are in the resolver cache. An individual negative cache entry represents one of the following results:

A host-name-to-IPv4-address resolver query to a specific name server, in which the name server indicated that the target host name does not have associated IPv4 addresses.
A host-name-to-IPv6-address resolver query to a specific name server, in which the name server indicated that the target host name does not have associated IPv6 addresses.
An IP-address-to-host-name resolver query to a specific name server, in which the name server indicated that the target IP address does not have associated host name value. The IP address can be either an IPv4 address or an IPv6 address.

A: Displays the total number of A negative cache entries that are currently in the resolver cache that were created as a result of host-name-to-IPv4-address resolver queries that did not return any IPv4 addresses. An individual A negative cache entry contains the results of one host-name-to-IPv4-address resolver query to a specific name server.
AAAA: Displays the total number of AAAA negative cache entries that are currently in the resolver cache that were created as a result of host-name-to-IPv6 address resolver queries that did not return any IPv6 addresses. An individual AAAA negative cache entry contains the results of one host-name-to-IPv6-address resolver query to a specific name server.
PTR: Displays the total number of PTR negative cache entries that are currently in the resolver cache that were created as a result of IP-address-to-host-name resolver queries that did not return a host name. An individual PTR negative cache entry contains the results of one IP-address-to-host-name resolver query to a specific name server. The target IP address can be either an IPv4 address or an IPv6 address.

Queries: Displays the total number of instances in which a query to the resolver cache services was attempted.
Guideline: A single resolver API call, for example, Getaddrinfo, might result in multiple queries to the resolver cache. Separate cache queries are attempted for IPv4 and IPv6 information. Separate cache queries are also attempted for different domains if the SEARCH resolver configuration statement specifies that different domains should be appended to the input host name value for search purposes.
Hits: Displays the total number of instances in which a query of the resolver cache provided response information about the target resource. The response information represents either DNS reply information that had been cached, or it represents an indication that negative cache information existed for the target resource.
SuccessRatio: Displays the percentage of cache queries that successfully provided response information. This value is equal to the number of hits divided by the number of queries.

DNS address

Displays information about the number and the makeup of the records that are currently in the resolver cache that are associated with replies from the name server at the displayed IP address.

Total number of entries

Displays the total number of A, AAAA, and PTR cache entries that are currently in the resolver cache that were created as a result of DNS response information from this specific name server. This value includes both NX (negative cache) entries and non-NX entries.

Non-NX entries

Displays the total number of A, AAAA, and PTR cache entries that represent successful name or address resolution attempts, in the resolver cache as a result of DNS response information from this specific name server. An individual cache entry contains one of the following results:

A host-name-to-IPv4-address resolver query to a specific name server, for which the name server returned at least one IPv4 address.
A host-name-to-IPv6-address resolver query to a specific name server, for which the name server returned at least one IPv6 address.
An IP-address-to-host-name resolver query to a specific name server, for which the name server returned a host name.

A: Displays the total number of A cache entries that are currently in the resolver cache that were created as a result of a successful resolution attempt directed to this specific name server. An individual A cache entry contains the results of one host-name-to-IPv4-address resolver query, even if multiple IPv4 addresses were returned by the name server for the target host name.
AAAA: Displays the total number of AAAA cache entries that are currently in the resolver cache that were created as a result of a successful resolution attempt directed to this specific name server. An individual AAAA cache entry contains the results of one host-name-to-IPv6-address resolver query, even if multiple IPv6 addresses were returned by the name server for the target host name.
PTR: Displays the total number of PTR cache entries that are currently in the resolver cache that were created as a result of a successful resolution attempt directed to this specific name server. An individual PTR cache entry contains the results of one IP-address-to-host-name resolver query. The target IP address can be either an IPv4 address or an IPv6 address.

NX entries

Displays the total number of A, AAAA, and PTR negative cache entries in the resolver cache that were created as a result of DNS response information from this specific name server. An individual negative cache entry can contain any of the following results:

A host-name-to-IPv4-address resolver query to which the name server responded that the target host name has no associated IPv4 addresses.
A host-name-to-IPv6-address resolver query to which the name server responded that the target host name has no associated IPv6 addresses.
An IP-address-to-host-name resolver query to which the name server responded that the target IP address has no associated host name value. The IP address can be either IPv4 addresses or IPv6 addresses.

A: Displays the total number of A negative cache entries that are currently in the resolver cache that were created a result of host-name-to-IPv4-address resolver queries to this specific name server that did not return any IPv4 addresses. An individual A negative cache entry contains the results of one host-name-to-IPv4-address resolver query.
AAAA: Displays the total number of AAAA negative cache entries that are currently in the resolver cache that were created as a result of host-name-to-IPv6-address resolver queries to this specific name server that did not return any IPv6 addresses. An individual AAAA negative cache entry contains the results of one host-name-to-IPv6-address resolver query.
PTR: Displays the total number of PTR negative cache entries that are currently in the resolver cache that were created as a result of IP-address-to-host-name resolver queries to this specific name server that did not return any host name. An individual PTR negative cache entry contains the results of one IP-address-to-host-name resolver query. The target IP address can be either an IPv4 address or an IPv6 address.

References

Displays the total number of instances in which a query of the resolver cache examined the collection of cache entries that represents DNS response information from the name server that was specified by the DNS address in an attempt to find response information about the target resource.

Guideline: A single cache query attempt might result in multiple queries of different collections of information provided by the name server. You can use the NSINTERADDR resolver configuration statement to specify which name servers should be queried to obtain information about the target resource, and in which order they should be queried. The resolver cache uses the same NSINTERADDR list to determine which collections of information provided by the name server to examine for a specific cache query. If no response information is found in the collection of information that is provided by the first name server in the NSINTERADDR list, the collection of information that is provided by the second name server in the list is checked, and so on.

If the first name server in the NSINTERADDR list is the primary name server for the installation, the number of references for that name server should be much higher than the number of references for the other name servers in the list. Most of the resolver queries should, during normal operation, be directed to the primary name server, and therefore most information in the resolver cache should be provided by the primary name server. A comparatively small number of references for the primary name server, compared to the secondary name servers, suggests that the primary name server might not be active all the time, or that most of the cache queries are not successful, because the resolver cache is examining more than just the primary name server's collection of responses as part of a single cache query.

Hits

Displays the total number of instances in which a query of the resolver cache provided response information about the target resource that was created as a result of DNS response information from the name server that was specified by the DNS address. The response information representss either DNS reply information that had been cached, or it is an indication that negative cache information existed for the target resource.

DETAIL or DETAIL NEGATIVE reports

HostName to IPAddress translation

This banner indicates that the next set of cache entries that is being reported contains the results of resolver queries, such as Getaddrinfo and Gethostbyname, to translate a host name into one or more IP addresses.

HostName

Displays the host name that is used as the target resource to acquire the cache information that is in this entry.

DNS IPAddress

Displays the IP address of the name server that provided the response information about the host name that is contained in this cache entry.

DNS Record Type

Displays the record type of this cache entry. See the following possible values:

T_A: Indicates the result of an attempt to resolve a host name to an IPv4 address.
T_AAAA: Indicates the result of an attempt to resolve a host name to an IPv6 address.

Canonical Name

Displays the official DNS name for the host name. The name is provided as part of the DNS response in the form of a T_CNAME resource record. If this entry represents negative cache information, then the value *** NA *** is displayed.

Cache Time

Displays the time and date when the cache entry was created.

Expired Time

Displays the time and date after which the cache entry is no longer valid. A time-to-live (TTL) value is provided as part of the DNS response data, and that value indicates how long the response data can be trusted. You can use the resolver MAXTTL setup statement to change the TTL value that is returned by DNS. See MAXTTL statement information in z/OS Communications Server: IP Configuration Reference for details about the resolver MAXTTL setup statement.

Guideline: The resolver cache logic does not automatically delete cache entries when the TTL time expires. The cache entries are deleted when a subsequent query for the host name is received or they are deleted as part of periodic storage cleanup processing.

Hits

Displays the number of times that the information in this cache entry was used to respond to a cache query.

IPAddress

Displays one or more IP addresses that are associated with the host name. One cache entry is used to contain IPv4 addresses that are associated with a given host name, and a second entry is used to contain IPv6 addresses that are associated with a given host name. All of the addresses displayed for a host name are either all IPv4 addresses, or all IPv6 addresses, but never a mixture of both types of addresses. If this entry represents negative cache information, then the value *** NA *** is displayed instead of an IP address.

IPAddress to HostName translation

This banner indicates that the next set of cache entries that is being reported displays the results of resolver queries, such as Getnameinfo and Gethostbyaddr, to translate an IP address into a host name.

IPAddress

Displays the IP address that is used as the target resource to acquire the cache information in this entry.

DNS IPAddress

Displays the IP address of the name server that provided the response information about the IP address that is contained in this cache entry.

DNS Record Type

Displays the record type of this cache entry. The possible value is:

T_PTR: Indicates the result of an attempt to resolve an IP address to a host name.

Cache Time

Displays the time and date when the cache entry was created.

Expired Time

Displays the time and date when the cache entry is longer valid. A time-to-live (TTL) value is provided as part of the DNS response data; that value indicates how long the response data can be trusted. You can use the resolver MAXTTL setup statement to change the TTL value that is returned by DNS. See the MAXTTL statement information in z/OS Communications Server: IP Configuration Reference for details about the resolver MAXTTL setup statement.

Guideline: The resolver cache logic does not automatically delete cache entries when the TTL time expires. The cache entries are deleted when a subsequent query for the IP address is received, or they are deleted as part of periodic storage cleanup processing.

Hits

Displays the number of times that the information in this cache entry was used to respond to a cache query.

HostName

Displays the host name that is associated with the IP address.

If this entry represents negative cache information, then the value *** NA *** is displayed instead of an IP address.