06-02-2016
Quote:
Originally Posted by
rahul2662
Hello,
I am trying to develop a script to check for valid hostnames. Below are the prerequisites for a valid hostname which I got from wiki :
Hostnames are composed of series of labels concatenated with dots, as are all domain names. For example, "en.wikipedia.org" is a hostname. Each label must be between 1 and 63 characters long, and the entire hostname (including the delimiting dots but not a trailing dot) has a maximum of 253 ASCII characters.
The Internet standards (Requests for Comments) for protocols mandate that component hostname labels may contain only the ASCII letters 'a' through 'z' (in a case-insensitive manner), the digits '0' through '9', and the hyphen ('-'). The original specification of hostnames in RFC 952, mandated that labels could not start with a digit or with a hyphen, and must not end with a hyphen. However, a subsequent specification (RFC 1123) permitted hostname labels to start with digits. No other symbols, punctuation characters, or white space are permitted.
Could someone please help.
Thanks
Rahul
Hello Rahul,
Good to see you in forums
. Regarding above query I would like to say it completely depends on the organization like they are really following the mentioned rules/guidelines or not. Why not do a
ping test for each host and find out(means--> if a host is valid it will pass the test), please do let me know your thoughts on same.
Thanks,
R. Singh
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LEARN ABOUT ULTRIX
ethers
ethers(5) File Formats Manual ethers(5)
Name
ethers - database that maps Ethernet addresses to hostnames
Description
The file is used in conjunction with the reverse address resolution protocol daemon, to map Ethernet addresses to hostnames. It contains
information about the known (48-bit) Ethernet addresses of hosts on the Internet.
For each host on an Ethernet, a single line should be present in the file with the following information:
Ethernet-address official-host-name
Items are separated by one or more spaces or tabs. A number sign (#) indicates the beginning of a comment that extends to the end of line.
The standard form for Ethernet addresses is:
x:x:x:x:x:x
The x is a hexadecimal number between 0 and ff, representing 1 byte. The address bytes are always in network order.
Hostnames can contain any printable character other than a space, tab, newline, or number sign (#).
Hostnames in the file should correspond to the hostnames in the file or to those provided by the name service.
Examples
The following is a sample file: 08:00:20:01:e5:1c host1 # Comments go here 08:00:20:01:d0:4c host2 # Comments go
here 08:00:20:01:e0:1d host3 # Comments go here 08:00:20:00:c2:4e host4 # Comments go here
See Also
ethers(3n), hosts(5), rarpd(8c)
Introduction to Networking and Distributed System Services
ethers(5)