What is Hostent structure?
The hostent structure is used by functions to store information about a given host, such as host name, IPv4 address, and so forth. An application should never attempt to modify this structure or to free any of its components.
What is the use of Gethostbyname?
The gethostbyname function returns a pointer to a hostent structure—a structure allocated by Windows Sockets. The hostent structure contains the results of a successful search for the host specified in the name parameter.
What is Gethostbyname in socket?
The gethostbyname socket function returns information about a host specified by a host name.
Which service does Gethostbyname internally consult?
The domain name queries carried out by gethostbyname() and gethostbyaddr() rely on the Name Service Switch (nsswitch. conf(5)) configured sources or a local name server (named(8)). The default action is to query the Name Service Switch (nsswitch.
What is Gethostbyname () and gethostbyaddr ()?
The gethostbyaddr() function need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe. The gethostbyname() function shall return an entry containing addresses of address family AF_INET for the host with name name. The gethostbyname() function need not be reentrant.
What is Af_inet?
AF_INET is an address family that is used to designate the type of addresses that your socket can communicate with (in this case, Internet Protocol v4 addresses). When you create a socket, you have to specify its address family, and then you can only use addresses of that type with the socket.
How do you test DDNS?
How to Test DDNS
- Click the Windows logo in the bottom-left corner of the screen, type “cmd” in the Search bar and press “Enter.” A black window opens.
- Type “nslookup” and press “Enter” after you change the directory in the same black window.
What is the return type of Gethostbyaddr ()?
The gethostbyaddr function returns a pointer to the hostent structure that contains the name and address corresponding to the given network address. The memory for the hostent structure returned by the gethostbyaddr function is allocated internally by the Winsock DLL from thread local storage.
What is Sock_seqpacket?
SOCK_SEQPACKET, for a connection-oriented socket that preserves message boundaries and delivers messages in the order that they were sent.” The standard permits that you get reordered packets with SOCK_DGRAM. (In other words, if an OS hands them to you in order, that is an implementation-specific feature.
What is DDNS function?
DDNS (Dynamic Domain Name System) allows us to overcome the issues related to Dynamic IP Addresses, in attempting to connect to a DVR somewhere on the Internet whose IP Address may change at any time.
Which protocols are used by DDNS?
Dynamic DNS and DHCP Typically, DDNS means the client device gets its IP settings from a dynamic host configuration protocol (DHCP) server. DHCP is a network protocol that allows the server to automatically assign an IP address—whether static or dynamic—to a computer.
What is Socklen_t in C?
DESCRIPTION. makes available a type, socklen_t, which is an unsigned opaque integral type of length of at least 32 bits. To forestall portability problems, it is recommended that applications should not use values larger than 232 – 1.
What is the hostent structure used for?
The hostent structure is used by functions to store information about a given host, such as host name, IPv4 address, and so forth. An application should never attempt to modify this structure or to free any of its components.
Is a struct hostent an array of strings?
P.S. struct hostent is not part of the C library, it is part of the socket library. No it is not an array of strings, it is an array of pointers (which point to strings). A pointer can be NULL (that is not point to anywhere).
What should an application not do with the hostent structure?
An application should never attempt to modify this structure or to free any of its components. Furthermore, only one copy of the hostent structure is allocated per thread, and an application should therefore copy any information that it needs before issuing any other Windows Sockets API calls.
What is the return type of the hostentstructure?
The routines return a hostentstructure containing the name of the host, its aliases, the address type (address family), and a NULL-terminated list of variable length addresses. The list of addresses is required because a host can have many addresses.