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utilizzo del DNS Primario e Secondario sui client RRS feed

  • Domanda

  • buongiorno,

    in ufficio è nata una discussione su come un client utilizza il dns primario e secondario; l'esempio piú significativo era: il server DNS primario non risponde piú alle richieste del client per 10 minuti (per quasliasi motivo), di conseguenza il client passa in automatico a interrogare il secondario. Ma il nostro dubbio era: il client rimane ad interrogare il DNS secondario per quanto tempo? cosa porterebbe il client a tornare ad interrogare il primario?

    grazie mille del supporto

    mercoledì 12 giugno 2013 06:15

Risposte

  • Ciao Alessio, forse una lettura al documento DNS Processes and Interactions può esserti utile.

    In particolare questa parte:

    1. The DNS Client service sends the name query to the first DNS server on the preferred adapter’s list of DNS servers and waits one second for a response.

    2. If the DNS Client service does not receive a response from the first DNS server within one second, it sends the name query to the first DNS servers on all adapters that are still under consideration and waits two seconds for a response.

    3. If the DNS Client service does not receive a response from any DNS server within two seconds, the DNS Client service sends the query to all DNS servers on all adapters that are still under consideration and waits another two seconds for a response.

    4. If the DNS Client service still does not receive a response from any DNS server, it sends the name query to all DNS servers on all adapters that are still under consideration and waits four seconds for a response.

    5. If it the DNS Client service does not receive a response from any DNS server, the DNS client sends the query to all DNS servers on all adapters that are still under consideration and waits eight seconds for a response.


    If the DNS Client service receives a positive response, it stops querying for the name, adds the response to the cache and returns the response to the client.

    If the DNS Client service has not received a response from any server within eight seconds, the DNS Client service responds with a timeout. Also, if it has not received a response from any DNS server on a specified adapter, then for the next 30 seconds, the DNS Client service responds to all queries destined for servers on that adapter with a timeout and does not query those servers.

    If at any point the DNS Client service receives a negative response from a server, it removes every server on that adapter from consideration during this search. For example, if in step 2, the first server on Alternate Adapter A gave a negative response, the DNS Client service would not send the query to any other server on the list for Alternate Adapter A.

    The DNS Client service keeps track of which servers answer name queries more quickly, and it moves servers up or down on the list based on how quickly they reply to name queries.

    Saluti

    Nino

    mercoledì 12 giugno 2013 12:11
    Moderatore

Tutte le risposte

  • Ciao, ma che discussioni fate in ufficio? ;)

    Ad ogni modo nel momento in cui non risponde più il primo DNS windows passa al secondario di solito se il primario non risponde per 15 minuti (ora non ricordo esattamente il tempo). Dopodichè utilizza il secondario finchè la macchina non viene restartata o lo stack del tcp/ip non viene resettato a quel punto riparte dal primo della lista. Diciamo che se il primario scende è una bella rogna in ogni caso...se poi è un DC...

    ciao!

    A.

    mercoledì 12 giugno 2013 09:06
    Moderatore
  • Ciao Alessio, forse una lettura al documento DNS Processes and Interactions può esserti utile.

    In particolare questa parte:

    1. The DNS Client service sends the name query to the first DNS server on the preferred adapter’s list of DNS servers and waits one second for a response.

    2. If the DNS Client service does not receive a response from the first DNS server within one second, it sends the name query to the first DNS servers on all adapters that are still under consideration and waits two seconds for a response.

    3. If the DNS Client service does not receive a response from any DNS server within two seconds, the DNS Client service sends the query to all DNS servers on all adapters that are still under consideration and waits another two seconds for a response.

    4. If the DNS Client service still does not receive a response from any DNS server, it sends the name query to all DNS servers on all adapters that are still under consideration and waits four seconds for a response.

    5. If it the DNS Client service does not receive a response from any DNS server, the DNS client sends the query to all DNS servers on all adapters that are still under consideration and waits eight seconds for a response.


    If the DNS Client service receives a positive response, it stops querying for the name, adds the response to the cache and returns the response to the client.

    If the DNS Client service has not received a response from any server within eight seconds, the DNS Client service responds with a timeout. Also, if it has not received a response from any DNS server on a specified adapter, then for the next 30 seconds, the DNS Client service responds to all queries destined for servers on that adapter with a timeout and does not query those servers.

    If at any point the DNS Client service receives a negative response from a server, it removes every server on that adapter from consideration during this search. For example, if in step 2, the first server on Alternate Adapter A gave a negative response, the DNS Client service would not send the query to any other server on the list for Alternate Adapter A.

    The DNS Client service keeps track of which servers answer name queries more quickly, and it moves servers up or down on the list based on how quickly they reply to name queries.

    Saluti

    Nino

    mercoledì 12 giugno 2013 12:11
    Moderatore