Configuring Domain Name System (DNS) Characteristics
If the access server cannot reach a learned name server because of gateway restrictions outside the server, it does not flag the unreachable name server. This can often cause name resolution to time out and fail. In this configuration use either the STUB or SLAVE name resolution mode.
Assigning DNS Server Addresses AutomaticallyThe DNS autoconfigure feature on the access server allows
The access server assigns a primary and secondary DNS server to the remote PPP client. The access server uses an algorithm to obtain the addresses of the DNS servers from its database.
The access server assigns only local name servers to PPP clients. It makes two passes through a list of local nameservers. The following table describes how the access server determines which name servers to assign to the PPP client:
Pass | Description | |
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1 | a) | The access server goes through a list of learned name servers |
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| and searches for name servers that are on its network (by using |
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| the access server’s subnet mask) and have a positive time to live |
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| (ttl). |
| b) | The access server goes through a list of |
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| name servers and searches for name servers that are on its |
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| network (by using the access server’s subnet mask) and have a |
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| positive time to live (ttl). |
| c) | The access server assigns the first valid name server as the |
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| Primary Nameserver and the second valid name server as the |
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| Secondary Nameserver. |
2If the access server does not find two valid name servers:
a)The access server goes through the list of learned name servers and searches for name servers with a positive time to live (ttl).
b)The access server goes through the list of
c)The access server assigns the first valid name server as the Primary Nameserver and the second valid name server as the Secondary Nameserver.
TCP/IP Network Characteristics