6.5.8 - DNS Server Configuration

Flashcards about DNS Server Configuration

Primary DNS Server

The zone records held on the server are editable.

Secondary DNS Server

The zone records are read-only copies and are maintained through a process of replication known as a zone transfer from a primary name server.

Important task for primary DNS

Update the serial number for each change made on the DNS server.

Advantage of secondary zones

Provides fault tolerance and load balancing.

UDP port 53

A DNS server is usually configured to listen for queries on this port.

TCP port 53

Allows larger record transfers (over 512 bytes), and might be required if IPv6 is deployed on the network or if the DNS servers are using a security protocol (DNSSEC).

Authoritative DNS Server

Holds complete records for a domain.

Cache-only Servers

Servers that don't maintain a zone (primary or secondary).

Non-authoritative answer

One that derives from a cached record, rather than directly from the zone records.

Time To Live (TTL)

Instructs resolvers how long a query result can be kept in cache, measured in seconds.

Setting a low TTL

Allows records to be updated more quickly but increases load on the server and latency on client connections to services.

DNS caching

Each application on a client computer might be configured to manage its own DNS cache.

Planning for a record change

Reducing the TTL in the period before the change, waiting for this change to propagate before updating the record, and then reverting to the original TTL value when the update has safely propagated.