There are many network commands on Windows and Linux systems which are frequently required. I have tried to compile all on them here on the site.
checkdnsrr — Check DNS records corresponding to a given Internet host name or IP address
closelog — Close connection to system logger
define_syslog_variables — Initializes all syslog related constants
dns_check_record — Alias of checkdnsrr
dns_get_mx — Alias of getmxrr
dns_get_record — Fetch DNS Resource Records associated with a hostname
fsockopen — Open Internet or Unix domain socket connection
gethostbyaddr — Get the Internet host name corresponding to a given IP address
gethostbyname — Get the IP address corresponding to a given Internet host name
gethostbynamel — Get a list of IP addresses corresponding to a given Internet host name
getmxrr — Get MX records corresponding to a given Internet host name
getprotobyname — Get protocol number associated with protocol name
getprotobynumber — Get protocol name associated with protocol number
getservbyname — Get port number associated with an Internet service and protocol
getservbyport — Get Internet service which corresponds to port and protocol
header — Send a raw HTTP header
headers_list — Returns a list of response headers sent (or ready to send)
headers_sent — Checks if or where headers have been sent
inet_ntop — Converts a packed internet address to a human readable representation
inet_pton — Converts a human readable IP address to its packed in_addr representation
ip2long — Converts a string containing an (IPv4) Internet Protocol dotted address into a proper address
long2ip — Converts an (IPv4) Internet network address into a string in Internet standard dotted format
openlog — Open connection to system logger
pfsockopen — Open persistent Internet or Unix domain socket connection
setcookie — Send a cookie
setrawcookie — Send a cookie without urlencoding the cookie value
socket_get_status — Alias of stream_get_meta_data
socket_set_blocking — Alias of stream_set_blocking
socket_set_timeout — Alias of stream_set_timeout
syslog — Generate a system log message
