DNS uses both User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) on all specified ports to serve the DNS queries. UDP is preferred because it is fast and has low overhead. A DNS query is a single request from the DNS client followed by a single reply from the server.

## DNS Port

- IPv4 Ports: DNS port for IP version 4.
- IPv6 Ports: DNS port for IP version 6.

## Service Time

- No Service Time: No service time delay is applied. Helps in doing max load testing.
- Exponential Random: Exponential random service time with median of specified milliseconds is applied. For exponential random distribution, median is roughly around 1/4th of the mean. This takes a random value equivalent to median time.
- Constant: A constant service time of specified milliseconds. Helps in doing controlled tests.
- Uniform Distribution: It is more Realistic. The value is a random value between the minimum and maximum time defined. Min should be less than or equal to Max.

## Response Settings

Send response using default.com zone if not found in the zone configuration. (Else domain does not exit (NXDOMAIN) will be send.

Notes :-

1. All zones need to be configured in $HPD_ROOT/zones directory. default.com is bundled with the release.
2. Zone file can have one or more lines in the following format:
3. Domain|QType|QClass|TTL(Seconds)|Answers1,Answers2
4. Supported QTypes are - A, AAAA, CNAME, MX, NS, PTR, SOA
5. QClass should be always IN
6. After any file changes, controller need to be restarted
7. For example, cavisson.com zone file can have following entries www.cavisson.com|A|IN|86400|10.10.10.1

## Error Simulation

- Percentage:Value in percent for which user wants the user defined response in case of error simulation.
- Response Code User defined response code in case of Error simulation.
- Response Code Types
  1. Format error - The name server was unable to interpret the query.
  2. Server failure - The name server was unable to process this query due to a problem with the name server.
  3. Name Error - Meaningful only for responses from an authoritative name server, this code signifies that the domain name referenced in the query does not exist.
  4. Not Implemented - The name server does not support the requested kind of query.
  5. Refused - The name server refuses to perform the specified operation for policy reasons. For example, a name server may not wish to provide the information to the particular requester, or a name server may not wish to perform a particular operation (e.g., zone transfer) for particular data.

Note:- Error Simulation will be applicable only if response setting is disabled