Axel AX3000 65 User's Manual Manual de usuario descargar pdf (Pagina 235)

Appendix

AX3000 - User's Manual 223

Example of name resolutions: looking at the host table in Chapter 3.1.3 the

name resolution attempts are:

- as400: this is not a full name, the resolution is first made with the first

DNS domain (as400.servers.axel.com). Then, in event of failure, with the

second DNS domain (as400.terminals.axel.com). Then, in event of

failure, the resolution is made with the name itself (as400).

- linux: an IP address is associated. No DNS resolution.

- www.axel.com: this is a full name. The resolution is first made with the

name itself (www.axel.com). Then, in event of failure, the resolution is

made with the first DNS domain (www.axel.com.servers.axel.com). Then,

in event of failure, with the second DNS domain

(www.axel.com.terminals.axel.com).

b) Resolution Method

To resolve a name, the AX3000 sends DNS requests to the DNS server(s).

If a DNS server sends back a positive response, then the IP address is found

and the resolution operation is completed. If not two cases of failure are

possible:

- Receiving a negative response: the name is not known by this DNS

server. The AX3000 will retry with a new DNS request or with the second

DNS server.

- No response (time-out): after a few seconds the DNS server has not

sent back a response. The AX3000 resends the same request to the

DNS server.

Note: after 4 time-out errors on the same DNS server, this server is

"removed" from the resolution operation.

Note: if a response previously considered as a time-out error is received, this

response is treated as a valid response (positive or negative).

The AX3000 requests a recursive search to the DNS servers (and not iterative

search). This means that the DNS server must search itself for a DNS server

which is able to resolve the required name.

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Axel AX3000 65 User's Manual Manual de usuario Pagina 235