Discussion:
hostdb question
Dk Jack
2018-10-17 21:15:40 UTC
Permalink
Hi,
I am looking at the hostdb configuration and I need some clarification on
the configuration. In particular I have questions about these two
configuration parameters.

proxy.config.hostdb.host_file.path
proxy.config.hostdb.strict_round_robin

I am trying to understand how hostdb round_robin configuration works. In my
setup, I am trying to reach multiple origin servers. I am using the same
domain name for all my origin servers. In my remap, I am using this name.
Since each of my origin servers has a different IP, I was hoping to use the
strict_round_robing configuration to distribute the load amongst the origin
servers.

The documentation for the first says that the format for host_file.path is
similar to 'hosts' file. However as per the answers for this query...

https://serverfault.com/questions/429839/assign-multiple-ips-to-1-entry-in-hosts-file

The hosts file doesn't support having multiple IPs for the same domain.
Does ATS hostdb behave differently i.e. similar to a DNS server. I am
asking this, because ATS has the hostdb round robin configuration.

BTW, this configuration works with an DNS server with strict round robing
enabled for my origin server domain. I am trying to get the same thing
working with hostdb since I want to avoid DNS round trip because my IPs are
fairly fixed.

Thanks for the help.

Dk.
Aaron Canary
2018-10-18 19:13:21 UTC
Permalink
The code parsing and storing the host_file only keeps 1 IpAddr per
hostname.
In order to use proxy.config.hostdb.strict_round_robin, the record must
come through DNS.

*I am trying to get the same thing working with hostdb since I want to
avoid DNS round trip because my IPs are fairly fixed.*
You could try setting a long ttl (like 5 minutes) on your DNS response
record, which will cause HostDB to cache the IP record for that long. DNS
is not repeated until that HostDB record is expired.

If you don't have control of the DNS ttl, then you can override it with
something like

# set minimum IP ttl to 10 seconds
proxy.config.hostdb.ttl_mode INT 3
proxy.config.hostdb.timeout INT 10


https://docs.trafficserver.apache.org/en/8.0.x/admin-guide/files/records.config.en.html?highlight=ttl_mode#proxy.config.hostdb.ttl_mode


I hope that helps.
Hi,
I am looking at the hostdb configuration and I need some clarification on
the configuration. In particular I have questions about these two
configuration parameters.
proxy.config.hostdb.host_file.path
proxy.config.hostdb.strict_round_robin
I am trying to understand how hostdb round_robin configuration works. In my
setup, I am trying to reach multiple origin servers. I am using the same
domain name for all my origin servers. In my remap, I am using this name.
Since each of my origin servers has a different IP, I was hoping to use the
strict_round_robing configuration to distribute the load amongst the origin
servers.
The documentation for the first says that the format for host_file.path is
similar to 'hosts' file. However as per the answers for this query...
https://serverfault.com/questions/429839/assign-multiple-ips-to-1-entry-in-hosts-file
The hosts file doesn't support having multiple IPs for the same domain.
Does ATS hostdb behave differently i.e. similar to a DNS server. I am
asking this, because ATS has the hostdb round robin configuration.
BTW, this configuration works with an DNS server with strict round robing
enabled for my origin server domain. I am trying to get the same thing
working with hostdb since I want to avoid DNS round trip because my IPs are
fairly fixed.
Thanks for the help.
Dk.
--
Aaron Canary
ATS - Senior Software Engineer
Alan Carroll
2018-10-18 19:46:12 UTC
Permalink
Unfortunately multiple addresses per host in a host file used to work but
was broken in the last HostDB update. I don't think it would be that hard
to put back.
Post by Aaron Canary
The code parsing and storing the host_file only keeps 1 IpAddr per
hostname.
In order to use proxy.config.hostdb.strict_round_robin, the record must
come through DNS.
*I am trying to get the same thing working with hostdb since I want to
avoid DNS round trip because my IPs are fairly fixed.*
You could try setting a long ttl (like 5 minutes) on your DNS response
record, which will cause HostDB to cache the IP record for that long. DNS
is not repeated until that HostDB record is expired.
If you don't have control of the DNS ttl, then you can override it with
something like
# set minimum IP ttl to 10 seconds
proxy.config.hostdb.ttl_mode INT 3
proxy.config.hostdb.timeout INT 10
https://docs.trafficserver.apache.org/en/8.0.x/admin-guide/files/records.config.en.html?highlight=ttl_mode#proxy.config.hostdb.ttl_mode
I hope that helps.
Hi,
I am looking at the hostdb configuration and I need some clarification on
the configuration. In particular I have questions about these two
configuration parameters.
proxy.config.hostdb.host_file.path
proxy.config.hostdb.strict_round_robin
I am trying to understand how hostdb round_robin configuration works. In
my
setup, I am trying to reach multiple origin servers. I am using the same
domain name for all my origin servers. In my remap, I am using this name.
Since each of my origin servers has a different IP, I was hoping to use
the
strict_round_robing configuration to distribute the load amongst the
origin
servers.
The documentation for the first says that the format for host_file.path
is
similar to 'hosts' file. However as per the answers for this query...
https://serverfault.com/questions/429839/assign-multiple-ips-to-1-entry-in-hosts-file
The hosts file doesn't support having multiple IPs for the same domain.
Does ATS hostdb behave differently i.e. similar to a DNS server. I am
asking this, because ATS has the hostdb round robin configuration.
BTW, this configuration works with an DNS server with strict round robing
enabled for my origin server domain. I am trying to get the same thing
working with hostdb since I want to avoid DNS round trip because my IPs
are
fairly fixed.
Thanks for the help.
Dk.
--
Aaron Canary
ATS - Senior Software Engineer
--
*Beware the fisherman who's casting out his line in to a dried up riverbed.*
*Oh don't try to tell him 'cause he won't believe. Throw some bread to the
ducks instead.*
*It's easier that way. *- Genesis : Duke : VI 25-28
Dk Jack
2018-10-18 21:08:32 UTC
Permalink
Thanks Alan, that’d be awesome if we can bring it back.
Post by Alan Carroll
Unfortunately multiple addresses per host in a host file used to work but
was broken in the last HostDB update. I don't think it would be that hard
to put back.
Post by Aaron Canary
The code parsing and storing the host_file only keeps 1 IpAddr per
hostname.
In order to use proxy.config.hostdb.strict_round_robin, the record must
come through DNS.
*I am trying to get the same thing working with hostdb since I want to
avoid DNS round trip because my IPs are fairly fixed.*
You could try setting a long ttl (like 5 minutes) on your DNS response
record, which will cause HostDB to cache the IP record for that long. DNS
is not repeated until that HostDB record is expired.
If you don't have control of the DNS ttl, then you can override it with
something like
# set minimum IP ttl to 10 seconds
proxy.config.hostdb.ttl_mode INT 3
proxy.config.hostdb.timeout INT 10
https://docs.trafficserver.apache.org/en/8.0.x/admin-guide/files/records.config.en.html?highlight=ttl_mode#proxy.config.hostdb.ttl_mode
I hope that helps.
Hi,
I am looking at the hostdb configuration and I need some clarification on
the configuration. In particular I have questions about these two
configuration parameters.
proxy.config.hostdb.host_file.path
proxy.config.hostdb.strict_round_robin
I am trying to understand how hostdb round_robin configuration works. In
my
setup, I am trying to reach multiple origin servers. I am using the same
domain name for all my origin servers. In my remap, I am using this name.
Since each of my origin servers has a different IP, I was hoping to use
the
strict_round_robing configuration to distribute the load amongst the
origin
servers.
The documentation for the first says that the format for host_file.path
is
similar to 'hosts' file. However as per the answers for this query...
https://serverfault.com/questions/429839/assign-multiple-ips-to-1-entry-in-hosts-file
The hosts file doesn't support having multiple IPs for the same domain.
Does ATS hostdb behave differently i.e. similar to a DNS server. I am
asking this, because ATS has the hostdb round robin configuration.
BTW, this configuration works with an DNS server with strict round robing
enabled for my origin server domain. I am trying to get the same thing
working with hostdb since I want to avoid DNS round trip because my IPs
are
fairly fixed.
Thanks for the help.
Dk.
--
Aaron Canary
ATS - Senior Software Engineer
--
*Beware the fisherman who's casting out his line in to a dried up riverbed.*
*Oh don't try to tell him 'cause he won't believe. Throw some bread to the
ducks instead.*
*It's easier that way. *- Genesis : Duke : VI 25-28
Leif Hedstrom
2018-10-18 21:42:05 UTC
Permalink
There’s also a feature to let ATS use an expired DNS record while updating it. It’s very useful, I use it all the time.

— Leif
Post by Alan Carroll
Unfortunately multiple addresses per host in a host file used to work but
was broken in the last HostDB update. I don't think it would be that hard
to put back.
Post by Aaron Canary
The code parsing and storing the host_file only keeps 1 IpAddr per
hostname.
In order to use proxy.config.hostdb.strict_round_robin, the record must
come through DNS.
*I am trying to get the same thing working with hostdb since I want to
avoid DNS round trip because my IPs are fairly fixed.*
You could try setting a long ttl (like 5 minutes) on your DNS response
record, which will cause HostDB to cache the IP record for that long. DNS
is not repeated until that HostDB record is expired.
If you don't have control of the DNS ttl, then you can override it with
something like
# set minimum IP ttl to 10 seconds
proxy.config.hostdb.ttl_mode INT 3
proxy.config.hostdb.timeout INT 10
https://docs.trafficserver.apache.org/en/8.0.x/admin-guide/files/records.config.en.html?highlight=ttl_mode#proxy.config.hostdb.ttl_mode
I hope that helps.
Hi,
I am looking at the hostdb configuration and I need some clarification on
the configuration. In particular I have questions about these two
configuration parameters.
proxy.config.hostdb.host_file.path
proxy.config.hostdb.strict_round_robin
I am trying to understand how hostdb round_robin configuration works. In
my
setup, I am trying to reach multiple origin servers. I am using the same
domain name for all my origin servers. In my remap, I am using this name.
Since each of my origin servers has a different IP, I was hoping to use
the
strict_round_robing configuration to distribute the load amongst the
origin
servers.
The documentation for the first says that the format for host_file.path
is
similar to 'hosts' file. However as per the answers for this query...
https://serverfault.com/questions/429839/assign-multiple-ips-to-1-entry-in-hosts-file
The hosts file doesn't support having multiple IPs for the same domain.
Does ATS hostdb behave differently i.e. similar to a DNS server. I am
asking this, because ATS has the hostdb round robin configuration.
BTW, this configuration works with an DNS server with strict round robing
enabled for my origin server domain. I am trying to get the same thing
working with hostdb since I want to avoid DNS round trip because my IPs
are
fairly fixed.
Thanks for the help.
Dk.
--
Aaron Canary
ATS - Senior Software Engineer
--
*Beware the fisherman who's casting out his line in to a dried up riverbed.*
*Oh don't try to tell him 'cause he won't believe. Throw some bread to the
ducks instead.*
*It's easier that way. *- Genesis : Duke : VI 25-28
Dk Jack
2018-10-18 21:07:35 UTC
Permalink
Thanks Aaron! That’s what I needed.

Bhasker.
Post by Aaron Canary
The code parsing and storing the host_file only keeps 1 IpAddr per
hostname.
In order to use proxy.config.hostdb.strict_round_robin, the record must
come through DNS.
*I am trying to get the same thing working with hostdb since I want to
avoid DNS round trip because my IPs are fairly fixed.*
You could try setting a long ttl (like 5 minutes) on your DNS response
record, which will cause HostDB to cache the IP record for that long. DNS
is not repeated until that HostDB record is expired.
If you don't have control of the DNS ttl, then you can override it with
something like
# set minimum IP ttl to 10 seconds
proxy.config.hostdb.ttl_mode INT 3
proxy.config.hostdb.timeout INT 10
https://docs.trafficserver.apache.org/en/8.0.x/admin-guide/files/records.config.en.html?highlight=ttl_mode#proxy.config.hostdb.ttl_mode
I hope that helps.
Hi,
I am looking at the hostdb configuration and I need some clarification on
the configuration. In particular I have questions about these two
configuration parameters.
proxy.config.hostdb.host_file.path
proxy.config.hostdb.strict_round_robin
I am trying to understand how hostdb round_robin configuration works. In my
setup, I am trying to reach multiple origin servers. I am using the same
domain name for all my origin servers. In my remap, I am using this name.
Since each of my origin servers has a different IP, I was hoping to use the
strict_round_robing configuration to distribute the load amongst the origin
servers.
The documentation for the first says that the format for host_file.path is
similar to 'hosts' file. However as per the answers for this query...
https://serverfault.com/questions/429839/assign-multiple-ips-to-1-entry-in-hosts-file
The hosts file doesn't support having multiple IPs for the same domain.
Does ATS hostdb behave differently i.e. similar to a DNS server. I am
asking this, because ATS has the hostdb round robin configuration.
BTW, this configuration works with an DNS server with strict round robing
enabled for my origin server domain. I am trying to get the same thing
working with hostdb since I want to avoid DNS round trip because my IPs are
fairly fixed.
Thanks for the help.
Dk.
--
Aaron Canary
ATS - Senior Software Engineer
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