DNS Class
Properties Methods Events Config Settings Errors
The DNS class is used to query DNS for record information.
Syntax
ipworks.DNS
Remarks
The DNS class queries a DNS server for records as specified in RFC 1035 and other relevant RFCs. The class property QueryType indicates the record to be queried. Calling Query will initiate the query.
Once the query is complete, a single Response event will fire and the record properties will be filled. StatusCode is the server's success or fail code, and Status is a standard string interpretation of the code.
The records are contained in the Records collection. The programming interface is designed to allow a full walk of the records in the DNS response, including provisions for handling new record types.
The class operates synchronously by default (i.e., it waits for a response before returning control to the caller); however, the class also may operate asynchronously (i.e., return control immediately), by setting Timeout to 0. Please see the Timeout property for more information.
Property List
The following is the full list of the properties of the class with short descriptions. Click on the links for further details.
DNSPort | This is the port to connect to on the DNS server. |
DNSServer | This is the address of the DNS server. |
Idle | This property specifies the current status of the class. |
LocalHost | This property includes the name of the local host or user-assigned IP interface through which connections are initiated or accepted. |
Protocol | This protocol is used for the DNS request. |
QueryType | This is the type of record to query. |
Records | This is the collection of records in the last response. |
RecordSource | The source of records provided in the Records properties. |
Recursive | This determines whether to ask the DNSServer to recursively query other servers. |
RequestId | This is the Id of the current DNS request. |
Status | This is a standard string interpretation of StatusCode . |
StatusCode | This contains the success or error code for the DNS query. |
Timeout | This property includes the timeout for the class. |
Method List
The following is the full list of the methods of the class with short descriptions. Click on the links for further details.
Config | Sets or retrieves a configuration setting. |
DoEvents | This method processes events from the internal message queue. |
GetFieldValue | This gets the value of the field indicated from a record. |
Interrupt | This method interrupts the current method. |
Query | This method queries a domain. |
Reset | This method will reset the class. |
Event List
The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.
Error | Fired when information is available about errors during data delivery. |
Log | This event fires once for each log message. |
Response | This event fires after a DNS query. |
SSLServerAuthentication | This event fires when connecting to the server. |
SSLStatus | This shows the progress of the secure connection. |
Config Settings
The following is a list of config settings for the class with short descriptions. Click on the links for further details.
ConnectionMode | Sets the connection mode for the DNS query. |
DNSProtocolLog | Returns a 'nslookup' style log. |
DoHMethod | Specifies the DNS over HTTPS method. |
ResponseTruncated | Whether the response is truncated. |
UseIDNs | Whether to encode hostnames to internationalized domain names. |
CaptureIPPacketInfo | Used to capture the packet information. |
DelayHostResolution | Whether the hostname is resolved when RemoteHost is set. |
DestinationAddress | Used to get the destination address from the packet information. |
DontFragment | Used to set the Don't Fragment flag of outgoing packets. |
LocalHost | The name of the local host through which connections are initiated or accepted. |
LocalPort | The port in the local host where the class binds. |
MaxPacketSize | The maximum length of the packets that can be received. |
QOSDSCPValue | Used to specify an arbitrary QOS/DSCP setting (optional). |
QOSTrafficType | Used to specify QOS/DSCP settings (optional). |
ShareLocalPort | If set to True, allows more than one instance of the class to be active on the same local port. |
UseConnection | Determines whether to use a connected socket. |
UseIPv6 | Whether or not to use IPv6. |
AbsoluteTimeout | Determines whether timeouts are inactivity timeouts or absolute timeouts. |
FirewallData | Used to send extra data to the firewall. |
InBufferSize | The size in bytes of the incoming queue of the socket. |
OutBufferSize | The size in bytes of the outgoing queue of the socket. |
BuildInfo | Information about the product's build. |
GUIAvailable | Whether or not a message loop is available for processing events. |
LicenseInfo | Information about the current license. |
MaskSensitiveData | Whether sensitive data is masked in log messages. |
UseDaemonThreads | Whether threads created by the class are daemon threads. |
UseInternalSecurityAPI | Whether or not to use the system security libraries or an internal implementation. |
DNSPort Property (DNS Class)
This is the port to connect to on the DNS server.
Syntax
public int getDNSPort(); public void setDNSPort(int DNSPort);
Default Value
53
Remarks
This property contains the port to connect to on the DNS server. A valid port number (a value between 1 and 65535) is required for the connection to take place. The property must be set before a connection is attempted and cannot be changed once a connection is established. Any attempt to change this property while connected will fail with an error.
This property is not available at design time.
DNSServer Property (DNS Class)
This is the address of the DNS server.
Syntax
public String getDNSServer(); public void setDNSServer(String DNSServer);
Default Value
""
Remarks
This property contains the address of the DNS server. The class attempts to find the default DNS server for the machine where it is installed, and provide it in the DNSServer property. You may change it to any particular DNS server you want to query. While any internet host running a DNS service will suffice, it is preferable to use either the DNS server for your network or the DNS server for the domain that you are querying.
If the class cannot determine the default DNS server address, the property value will be an empty string.
Note: Automatic discovery of the default DNS server is not supported in the Java edition.
This property is not available at design time.
Idle Property (DNS Class)
This property specifies the current status of the class.
Syntax
public boolean isIdle();
Default Value
True
Remarks
Idle will be False if the component is currently busy (communicating or waiting for an answer), and True at all other times.
This property is read-only.
LocalHost Property (DNS Class)
This property includes the name of the local host or user-assigned IP interface through which connections are initiated or accepted.
Syntax
public String getLocalHost(); public void setLocalHost(String localHost);
Default Value
""
Remarks
The LocalHost property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.
In multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.
If the class is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).
Note: LocalHost is not persistent. You must always set it in code, and never in the property window.
Protocol Property (DNS Class)
This protocol is used for the DNS request.
Syntax
public int getProtocol(); public void setProtocol(int protocol); Enumerated values: public final static int ptUDP = 0; public final static int ptTCP = 1; public final static int ptTLS = 2; public final static int ptHTTPS = 3;
Default Value
0
Remarks
This property specifies the protocol used for the DNS request when Query is called. Possible values include the following:
0 (ptUDP - default) | User Datagram Protocol (UDP) is used. This is the most commonly used DNS protocol. |
1 (ptTCP) | Transmission Control Protocol (TCP) is used. |
2 (ptTLS) | TCP with Transport Layer Security (TLS) is used. Set DNSPort to the port that the server uses for TLS connections. Typically this is port 853. |
3 (ptHTTPS) | HTTP is used. The DNS request is made over HTTP. DNSServer must be set to a URL of a server accepting DNS over HTTPS (DoH) requests. See the DoHMethod configuration setting for additional options when using this protocol. |
QueryType Property (DNS Class)
This is the type of record to query.
Syntax
public int getQueryType(); public void setQueryType(int queryType); Enumerated values: public final static int qtAddress = 1; public final static int qtNS = 2; public final static int qtMD = 3; public final static int qtMF = 4; public final static int qtCName = 5; public final static int qtSOA = 6; public final static int qtMailBox = 7; public final static int qtMailGroup = 8; public final static int qtMR = 9; public final static int qtNULL = 10; public final static int qtWKS = 11; public final static int qtPointer = 12; public final static int qtHostInfo = 13; public final static int qtMailInfo = 14; public final static int qtMX = 15; public final static int qtText = 16; public final static int qtRP = 17; public final static int qtAFSDB = 18; public final static int qtX25 = 19; public final static int qtISDN = 20; public final static int qtRT = 21; public final static int qtAAAA = 28; public final static int qtSRV = 33; public final static int qtNAPTR = 35; public final static int qtCERT = 37; public final static int qtRevLookup = 100;
Default Value
1
Remarks
Before a query is attempted, this property must be set to the desired record type. The records are defined as follows:
qtAddress (1) | Address Records |
qtNS (2) | Name Server Records |
qtMD (3) | Mail Destination Records |
qtMF (4) | Mail Forwarder Records |
qtCName (5) | Canonical Name Records |
qtSOA (6) | Start Of Authority Records |
qtMailBox (7) | MailBox Records |
qtMailGroup (8) | Mail Group Records |
qtMR (9) | MailBox Rename Records |
qtNULL (10) | NULL Records |
qtWKS (11) | Well-Known Services Records |
qtPointer (12) | Pointer Records |
qtHostInfo (13) | Host Information Records |
qtMailInfo (14) | Mail Information Records |
qtMX (15) | Mail Exchange Records |
qtText (16) | Text Records |
qtRP (17) | Responsible Person Records |
qtAFSDB (18) | Service Records |
qtX25 (19) | X25 Records |
qtISDN (20) | ISDN Records |
qtRT (21) | Route Through Records |
qtAAAA (28) | AAAA Record |
qtSRV (33) | SRV Record (location of services) |
qtNAPTR (35) | NAPTR Record (Naming Authority Pointer) |
qtCERT (37) | Certificate Record (e.g., Stores PKIX, SPKI, PGP) |
qtRevLookup (100) | Reverse Lookup (Reverse Lookup) |
This property is not available at design time.
Records Property (DNS Class)
This is the collection of records in the last response.
Syntax
public DNSRecordList getRecords();
Remarks
Once the query is complete, a single Response event will fire. The following properties will contain the results:
StatusCode | The success or error code of the DNS query. |
Status | A standard string interpretation of StatusCode. |
Records | The Records in the last DNS response. |
RecordSource | The source (type) of records being listed. |
This collection is indexed from 0 to size -1.
Example (loop through all fields of all records)
For i = 0 to DNSControl.Records.Count - 1
For j = 0 to DNSControl.Records.FieldCount(i) - 1
DNSControl.Records(i).FieldIndex = j
DoSomethingWith(DNSControl.Records(i).FieldName, DNSControl.Records(i).FieldValue)
Next j
Next i
This property is read-only and not available at design time.
Please refer to the DNSRecord type for a complete list of fields.RecordSource Property (DNS Class)
The source of records provided in the Records properties.
Syntax
public int getRecordSource(); public void setRecordSource(int recordSource); Enumerated values: public final static int rsAnswerSection = 0; public final static int rsNameServerSection = 1; public final static int rsAdditionalRecordsSection = 2;
Default Value
0
Remarks
This property contains the source of records provided in the Records collection and can have one of the following values:
rsAnswerSection (0) | Records answering the question/query. |
rsNameServerSection (1) | Records pointing toward an authoritative name server. |
rsAdditionalRecordsSection (2) | Records holding additional information. |
This property is not available at design time.
Recursive Property (DNS Class)
This determines whether to ask the DNSServer to recursively query other servers.
Syntax
public boolean isRecursive(); public void setRecursive(boolean recursive);
Default Value
True
Remarks
If this property is True, the component will tell the DNS server to perform the query recursively. This means that if the DNS server does not have information about the domain being queried, it will send the request to another DNS server.
This property is not available at design time.
RequestId Property (DNS Class)
This is the Id of the current DNS request.
Syntax
public int getRequestId(); public void setRequestId(int requestId);
Default Value
1
Remarks
This property is the identifier of the request that generated the current response values. Each time the class makes a DNS query, it generates a unique request identifier to track the response.
If a custom value is needed for RequestId, the property must be set before sending a request. The class increments RequestId automatically after sending each request.
Note: The class throws an exception when a value that is not between 1 and 32,767 is specified.
This property is not available at design time.
Status Property (DNS Class)
This is a standard string interpretation of StatusCode .
Syntax
public String getStatus();
Default Value
""
Remarks
This property contains a standard string interpretation of StatusCode. For a list of valid error codes and their descriptions, please see the Error Codes section.
This property is read-only and not available at design time.
StatusCode Property (DNS Class)
This contains the success or error code for the DNS query.
Syntax
public int getStatusCode();
Default Value
0
Remarks
This property contains the success or error code for the DNS query. For a list of valid error codes and their descriptions, please see the Error Codes section.
This property is read-only and not available at design time.
Timeout Property (DNS Class)
This property includes the timeout for the class.
Syntax
public int getTimeout(); public void setTimeout(int timeout);
Default Value
60
Remarks
If the Timeout property is set to 0, all operations return immediately, potentially failing with a WOULDBLOCK error if data cannot be sent immediately.
If Timeout is set to a positive value, data is sent in a blocking manner and the class will wait for the operation to complete before returning control. The class will handle any potential WOULDBLOCK errors internally and automatically retry the operation for a maximum of Timeout seconds.
The class will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not freeze and remains responsive.
If Timeout expires, and the operation is not yet complete, the class throws an exception.
Note: By default, all timeouts are inactivity timeouts, that is, the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.
The default value for the Timeout property is 60 seconds.
Config Method (DNS Class)
Sets or retrieves a configuration setting.
Syntax
public String config(String configurationString);
Remarks
Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.
These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.
To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).
To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.
DoEvents Method (DNS Class)
This method processes events from the internal message queue.
Syntax
public void doEvents();
Remarks
When DoEvents is called, the class processes any available events. If no events are available, it waits for a preset period of time, and then returns.
GetFieldValue Method (DNS Class)
This gets the value of the field indicated from a record.
Syntax
public String getFieldValue(int recordIndex, String fieldName);
Remarks
This method will get the value of the DNS record field specified by FieldName from the DNS record at RecordIndex. If no such field exists for that record type, the component throws an exception.
Interrupt Method (DNS Class)
This method interrupts the current method.
Syntax
public void interrupt();
Remarks
If there is no method in progress, Interrupt simply returns, doing nothing.
Query Method (DNS Class)
This method queries a domain.
Syntax
public void query(String domain);
Remarks
This method will query the host Domain for any records of the type in QueryType. After the query, RequestId is the identifier corresponding to the request. Once the query is complete, a single Response event will fire. The following properties will contain the results:
StatusCode | The success or error code of the DNS query. |
Status | A standard string interpretation of StatusCode. |
Records | The Records in the last DNS response. |
RecordSource | The source (type) of records being listed. |
Reset Method (DNS Class)
This method will reset the class.
Syntax
public void reset();
Remarks
This method will reset the class's properties to their default values.
Error Event (DNS Class)
Fired when information is available about errors during data delivery.
Syntax
public class DefaultDNSEventListener implements DNSEventListener { ... public void error(DNSErrorEvent e) {} ... } public class DNSErrorEvent { public int errorCode; public String description; }
Remarks
The Error event is fired in case of exceptional conditions during message processing. Normally the class throws an exception.
The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.
Log Event (DNS Class)
This event fires once for each log message.
Syntax
public class DefaultDNSEventListener implements DNSEventListener { ... public void log(DNSLogEvent e) {} ... } public class DNSLogEvent { public int logLevel; public String message; public String logType; }
Remarks
This event fires once for each log message generated by the class. The verbosity is controlled by the LogLevel setting.
LogLevel indicates the level of message. Possible values are as follows:
0 (None) | No events are logged. |
1 (Info - default) | Informational events are logged. |
2 (Verbose) | Detailed data are logged. |
3 (Debug) | Debug data are logged. |
The value 1 (Info) logs basic information, including the URL, HTTP version, and status details.
The value 2 (Verbose) logs additional information about the request and response.
The value 3 (Debug) logs the headers and body for both the request and response, as well as additional debug information (if any).
Message is the log entry.
LogType identifies the type of log entry. Possible values are as follows:
- "Info"
- "RequestHeaders"
- "ResponseHeaders"
- "RequestBody"
- "ResponseBody"
- "ProxyRequest"
- "ProxyResponse"
- "FirewallRequest"
- "FirewallResponse"
Response Event (DNS Class)
This event fires after a DNS query.
Syntax
public class DefaultDNSEventListener implements DNSEventListener { ... public void response(DNSResponseEvent e) {} ... } public class DNSResponseEvent { public int requestId; public String domain; public int statusCode; public String description; public boolean authoritative; }
Remarks
The Response event will fire after a call to Query. The RequestId parameter contains the request Id associated with the original query. Domain is the domain of the query. The Authoritative parameter is true if the response is from an authoritative name server. If there is an error returned by the server, StatusCode and Description provide them.
Once the query is complete, a single Response event will fire. The following properties will contain the results:
StatusCode | The success or error code of the DNS query. |
Status | A standard string interpretation of StatusCode. |
Records | The Records in the last DNS response. |
RecordSource | The source (type) of records being listed. |
SSLServerAuthentication Event (DNS Class)
This event fires when connecting to the server.
Syntax
public class DefaultDNSEventListener implements DNSEventListener { ... public void SSLServerAuthentication(DNSSSLServerAuthenticationEvent e) {} ... } public class DNSSSLServerAuthenticationEvent { public String remoteAddress; public int remotePort; public byte[] certEncoded; public String certSubject; public String certIssuer; public String status; public boolean accept; //read-write }
Remarks
This event allows the client to decide whether or not to continue with the connection process. The Accept parameter recommends whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.
When Accept is False, Status shows why the verification failed (otherwise, Status contains the string "OK"). If the client decides to continue, you can override and accept the certificate by setting the Accept parameter to True.
RemoteAddress is the IP address of the server.
RemotePort is the source port of the server.
CertEncoded is the Base64-encoded certificate presented by the server.
CertSubject is the subject of the certificate presented by the server.
CertIssuer is the subject of the issuer of the certificate presented by the server.
Status is the status of the certificate.
Accept defines whether the certificate is accepted.
SSLStatus Event (DNS Class)
This shows the progress of the secure connection.
Syntax
public class DefaultDNSEventListener implements DNSEventListener { ... public void SSLStatus(DNSSSLStatusEvent e) {} ... } public class DNSSSLStatusEvent { public String remoteAddress; public int remotePort; public String message; }
Remarks
The event is fired for informational and logging purposes only. It is used to track the progress of the connection.
RemoteAddress is the IP address of the remote machine.
RemotePort is the port of the remote machine.
Message is the log message.
DNSRecord Type
This is a record that is returned by the DNS server.
Remarks
When a Query method is performed by the DNS class, the DNS server returns one or more DNSRecords containing information about the domain you specified. This information is contained in the different fields of the record.
Each record may have multiple FieldNames and corresponding FieldValues. You may iterate through these by setting the FieldIndex field.
Fields
Domain
String (read-only)
Default Value: ""
This field contains the domain name associated with the selected response record, at RecordIndex.
FieldCount
int (read-only)
Default Value: 0
This field contains the number of fields in the current record.
After a successful query, the field values for each record will be provided in the Records collection.
To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.
FieldIndex
int
Default Value: 1
This field contains the index of the selected field of the current record. FieldIndex valid values are from 0 to (FieldCount -1).
After a successful query, the field values for each record will be provided in the Records collection.
To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.
FieldName
String (read-only)
Default Value: "0"
This field contains the name of the field selected by FieldIndex. Field names are different depending on the record type. For example, an MX record type will contain two fields: PREFERENCE and EXCHANGE, but an SOA record type contains seven fields.
Field names:
A Records | ADDRESS |
NS Records | DNAME |
MD | MADNAME |
MF | MADNAME |
CNAME | CNAME |
SOA | MNAME |
SOA | RNAME |
SOA | SERIAL |
SOA | REFRESH |
SOA | RETRY |
SOA | EXPIRE |
SOA | MINIMUM |
MB | MADNAME |
MG | MGMNAME |
MR | NEWNAME |
NULL | NULL |
WKS | ADDRESS |
WKS | PROTOCOL |
WKS | SERVICEMAP |
PTR | PTRDNAME |
HINFO | CPU |
HINFO | OS |
MINFO | RMAILBX |
MINFO | EMAILBX |
MX | PREFERENCE |
MX | EXCHANGE |
TXT | TXT |
RP | MBOXDNAME |
RP | TXTDNAME |
AFSDB | SUBTYPE |
AFSDB | HOSTNAME |
X25 | PSDNADDRESS |
ISDN | ISDNADDRESS |
RT | PREFERENCE |
RT | INTERMEDIATE |
AAAA | ADDRESS |
SRV | PRIORITY |
SRV | WEIGHT |
SRV | PORT |
SRV | TARGET |
NAPTR | ORDER |
NAPTR | PRIORITY |
NAPTR | FLAGS |
NAPTR | SERVICES |
NAPTR | REGEXP |
NAPTR | REPLACEMENT |
FieldValue
String (read-only)
Default Value: ""
This field contains the value of the field selected by FieldIndex.
After a successful query, the field values for each record will be provided in the Records collection.
To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.
FieldValueB
byte[] (read-only)
Default Value: ""
This field contains the value of the field selected by FieldIndex.
After a successful query, the field values for each record will be provided in the Records collection.
To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.
RecordData
String (read-only)
Default Value: ""
This field contains the full record data as received from the DNS server.
After a successful query, the field values for each record will be provided in the Records collection.
To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.
RecordDataB
byte[] (read-only)
Default Value: ""
This field contains the full record data as received from the DNS server.
After a successful query, the field values for each record will be provided in the Records collection.
To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.
RecordType
int (read-only)
Default Value: 1
This field contains the record type.
Record types correspond to QueryType and are defined as follows:
rtAddress (1) | Address Record |
rtNS (2) | Name Server Record |
rtMD (3) | Mail Destination Record |
rtMF (4) | Mail Forwarder Record |
rtCName (5) | Canonical Name Record |
rtSOA (6) | Start of Authority Record |
rtMailBox (7) | MailBox Record |
rtMailGroup (8) | Mail Group Record |
rtMR (9) | MailBox Rename Record |
rtNULL (10) | NULL Record |
rtWKS (11) | Well-Known Services Record |
rtPointer (12) | Pointer Record |
rtHostInfo (13) | Host Information Record |
rtMailInfo (14) | Mail Information Record |
rtMX (15) | Mail Exchange Record |
rtText (16) | Text Record |
rtRP (17) | Responsible Person Record |
rtAFSDB (18) | Service Record |
rtX25 (19) | X25 Record |
rtISDN (20) | ISDN Record |
rtRT (21) | Route Through Record |
rtAAAA (28) | AAAA Record |
rtSRV (33) | SRV Record (Location of Services) |
rtNAPTR (35) | Naming Authority Pointer Record |
RecordTypeName
String (read-only)
Default Value: ""
This field contains the string representation of the current record type defined by RecordType.
A (1) | Address Record |
NS (2) | Name Server Record |
MD (3) | Mail Destination Record |
MF (4) | Mail Forwarder Record |
CName (5) | Canonical Name Record |
SOA (6) | Start of Authority Record |
MB (7) | MailBox Record |
MG (8) | Mail Group Record |
MR (9) | MailBox Rename Record |
NULL (10) | NULL Record |
WKS (11) | Well-Known Services Record |
PTR (12) | Pointer Record |
HINFO (13) | Host Information Record |
MINFO (14) | Mail Information Record |
MX (15) | Mail Exchange Record |
TXT (16) | Text Record |
RP (17) | Responsible Person Record |
AFSDB (18) | Service Record |
X25 (19) | X25 Record |
ISDN (20) | ISDN Record |
RT (21) | Route Through Record |
AAAA (28) | AAAA Record |
rtSRV (33) | SRV Record (Location of Services) |
NAPTR (35) | Naming Authority Pointer Record |
TTL
int (read-only)
Default Value: 0
This field contains the record Time to Live (TTL) value. The TTL specifies the time interval in seconds that the record is valid, or the time interval that the record can be cached before the DNS server should be queried again.
Constructors
public DNSRecord();
Config Settings (DNS Class)
The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.DNS Config Settings
The appropriate values are as follows:
0 | Auto-connection mode. Try UDP first, and if needed, retry with TCP automatically. |
1 | Always use UDP for queries (default setting). |
2 | Always use TCP for queries. Note: the DNS server must support TCP queries or this will fail. |
DNS.Config("DNSProtocolLog=true");
DNS.Query("www.nsoftware.com");
string myLog = DNS.Config("DNSProtocolLog");
The default value is False and no log will be constructed.
0 (default) | HTTP POST (DNS Wireformat) |
1 | HTTP GET (DNS Wireformat) |
2 | HTTP GET (JSON) |
The default value is False and the hostname will always be used exactly as specified.
UDP Config Settings
The default value for this setting is False.
Note: This configuration setting is available only in Windows.
The default value is false.
Note: This configuration setting is available only in Windows.
In multihomed hosts (machines with more than one IP interface), setting LocalHost to the value of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface.
If the class is connected, the LocalHost setting shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).
Setting this to 0 (default) enables the system to choose a port at random. The chosen port will be shown by LocalPort after the connection is established.
LocalPort cannot be changed once a connection is made. Any attempt to set this when a connection is active will generate an error.
This configuration setting is useful when trying to connect to services that require a trusted port on the client side. An example is the remote shell (rsh) service in UNIX systems.
Note: This configuration setting uses the qWAVE API and is available only on Windows 7, Windows Server 2008 R2, and later.
Note: This configuration setting uses the qWAVE API and is available only on Windows Vista and Windows Server 2008 or above.
Note: QOSTrafficType must be set before setting Active to True.
The default value for this setting is False.
The default value for this setting is False.
Socket Config Settings
Note: This option is not valid for User Datagram Protocol (UDP) ports.
Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the class is activated the InBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.
Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the class is activated the OutBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.
Base Config Settings
In some non-GUI applications, an invalid message loop may be discovered that will result in errant behavior. In these cases, setting GUIAvailable to false will ensure that the class does not attempt to process external events.
- Product: The product the license is for.
- Product Key: The key the license was generated from.
- License Source: Where the license was found (e.g., RuntimeLicense, License File).
- License Type: The type of license installed (e.g., Royalty Free, Single Server).
- Last Valid Build: The last valid build number for which the license will work.
This setting only works on these classes: AS3Receiver, AS3Sender, Atom, Client(3DS), FTP, FTPServer, IMAP, OFTPClient, SSHClient, SCP, Server(3DS), Sexec, SFTP, SFTPServer, SSHServer, TCPClient, TCPServer.
Setting this configuration setting to true tells the class to use the internal implementation instead of using the system security libraries.
This setting is set to false by default on all platforms.
Trappable Errors (DNS Class)
DNS Errors
100 | No records were found. |
220 | Invalid record index. |
221 | Invalid field index for record type. |
222 | Invalid record source. |
223 | Unknown record type. |
224 | Could not determine DNS server address. |
225 | Could not parse address. |
UDP Errors
104 | UDP is already Active. |
106 | You cannot change the LocalPort while the class is Active. |
107 | You cannot change the LocalHost at this time. A connection is in progress. |
109 | The class must be Active for this operation. |
112 | You cannot change MaxPacketSize while the class is Active. |
113 | You cannot change ShareLocalPort option while the class is Active. |
114 | You cannot change RemoteHost when UseConnection is set and the class Active. |
115 | You cannot change RemotePort when UseConnection is set and the class is Active. |
116 | RemotePort cannot be zero when UseConnection is set. Please specify a valid service port number. |
117 | You cannot change UseConnection while the class is Active. |
118 | Message cannot be longer than MaxPacketSize. |
119 | Message too short. |
434 | Unable to convert string to selected CodePage. |
SSL Errors
270 | Cannot load specified security library. |
271 | Cannot open certificate store. |
272 | Cannot find specified certificate. |
273 | Cannot acquire security credentials. |
274 | Cannot find certificate chain. |
275 | Cannot verify certificate chain. |
276 | Error during handshake. |
280 | Error verifying certificate. |
281 | Could not find client certificate. |
282 | Could not find server certificate. |
283 | Error encrypting data. |
284 | Error decrypting data. |
TCP/IP Errors
10004 | [10004] Interrupted system call. |
10009 | [10009] Bad file number. |
10013 | [10013] Access denied. |
10014 | [10014] Bad address. |
10022 | [10022] Invalid argument. |
10024 | [10024] Too many open files. |
10035 | [10035] Operation would block. |
10036 | [10036] Operation now in progress. |
10037 | [10037] Operation already in progress. |
10038 | [10038] Socket operation on nonsocket. |
10039 | [10039] Destination address required. |
10040 | [10040] Message is too long. |
10041 | [10041] Protocol wrong type for socket. |
10042 | [10042] Bad protocol option. |
10043 | [10043] Protocol is not supported. |
10044 | [10044] Socket type is not supported. |
10045 | [10045] Operation is not supported on socket. |
10046 | [10046] Protocol family is not supported. |
10047 | [10047] Address family is not supported by protocol family. |
10048 | [10048] Address already in use. |
10049 | [10049] Cannot assign requested address. |
10050 | [10050] Network is down. |
10051 | [10051] Network is unreachable. |
10052 | [10052] Net dropped connection or reset. |
10053 | [10053] Software caused connection abort. |
10054 | [10054] Connection reset by peer. |
10055 | [10055] No buffer space available. |
10056 | [10056] Socket is already connected. |
10057 | [10057] Socket is not connected. |
10058 | [10058] Cannot send after socket shutdown. |
10059 | [10059] Too many references, cannot splice. |
10060 | [10060] Connection timed out. |
10061 | [10061] Connection refused. |
10062 | [10062] Too many levels of symbolic links. |
10063 | [10063] File name is too long. |
10064 | [10064] Host is down. |
10065 | [10065] No route to host. |
10066 | [10066] Directory is not empty |
10067 | [10067] Too many processes. |
10068 | [10068] Too many users. |
10069 | [10069] Disc Quota Exceeded. |
10070 | [10070] Stale NFS file handle. |
10071 | [10071] Too many levels of remote in path. |
10091 | [10091] Network subsystem is unavailable. |
10092 | [10092] WINSOCK DLL Version out of range. |
10093 | [10093] Winsock is not loaded yet. |
11001 | [11001] Host not found. |
11002 | [11002] Nonauthoritative 'Host not found' (try again or check DNS setup). |
11003 | [11003] Nonrecoverable errors: FORMERR, REFUSED, NOTIMP. |
11004 | [11004] Valid name, no data record (check DNS setup). |