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Questions[ttl](server)

Martin Hope
wobbily_col
Asked: 2016-05-03 11:38:24 +0800 CST
  • 37

I am migrating our app from a cloud server at Rackspace t a dedicated server.

I want to bring the application down for ~5 minutes to copy the data from the cloud server to the dedicated server, so I don't want requests going to the old server after I have copied the data.

I want to point our DNS record at the new server, but the TTL was set to 24 hours. I have changed it to 300 seconds. Do I need to wait the 24 hours before updating the ip that domain points to / copying the data?

domain-name-system ttl rackspace
Martin Hope
Ade
Asked: 2012-05-16 03:02:47 +0800 CST
  • 24

I have discovered that I can set the TTL in Varnish as follows in my VCL file:

sub vcl_fetch {
    # 1 minute
    set obj.ttl = 1m;
}

But what is the default setting (assuming the backend server is setting no cache-control header) ?

cache varnish ttl
Martin Hope
Ryan Pendleton
Asked: 2011-04-16 12:04:09 +0800 CST
  • 29

Due to how many servers are involved in my network, I have a hard time keeping them all organized. Some of them don't have static IP's, so I thought it might be nice if I made a config.mydomain.com domain. On this domain, I could store A records and the IP for each of the servers. This is how I set it up:

s1.config.mydomain.com.     A   10.0.0.1    #ttl 60
s2.config.mydomain.com.     A   10.0.0.2    #ttl 60
s3.config.mydomain.com.     A   10.0.0.3    #ttl 60
# etc

Each of those records have a TTL of 60, in case I need to change an IP quickly, but I don't necessarily want clients connecting every 60 seconds to update. Now let's say I setup my domains to use them, like this:

mydomain.com.           CNAME   s2.config.mydomain.com.   #ttl 3600
mail.mydomain.com.      CNAME   s2.config.mydomain.com.   #ttl 10800
svn.mydomain.com.       CNAME   ns1.config.mydomain.com.  #ttl 21600

The TTLs for the CNAMES are higher, so let's say I go to mydomain.com. It asks my DNS server for the IP of mydomain.com, and my server returns CNAME s2.config.mydomain.com. Then it asks my server for the IP of s2.config.mydomain.com, and my server returns 10.0.0.1.

Would it cache the CNAME s2.config.mydomain.com record for 3600 seconds, and the A 10.0.0.1 record for 60 seconds? Meaning that every 60 seconds it will still ask my server for the IP address?

Or will it cache the see CNAME s2.config.mydomain.com, get the A 10.0.0.1, and cache them both for 3600 seconds.

If it's the first, I'll probably have to find another way to manage them, so I'm hoping it's the second, but I'm not sure. Do you know of a better way to keep track of them?

domain-name-system cname-record ttl
Martin Hope
Stefan Lasiewski
Asked: 2010-09-10 10:21:18 +0800 CST
  • 127

I would like to see the Time-To-Live (TTL) value for a CNAME record.

I have access to dig (on Apple Mac OS X), which gives me an answer like this:

% dig host.example.gov
<*SNIP*>
;; ANSWER SECTION:
host.example.gov.       43200   IN  CNAME   host1.example.gov.
host1.example.gov.      43200   IN  A       192.168.16.10

Is the value '43200' the TTL for this DNS record?

domain-name-system ttl dig
Martin Hope
Leonardo
Asked: 2009-07-13 21:23:38 +0800 CST
  • 58

We get the message “TTL expired in transit” when we try to ping to a server in a different network segment. When we run tracert, 4 ip addresses repeat themselves indefinitely:

14    60 ms    59 ms    60 ms  xxx.xxx.xxx.2
15    83 ms    81 ms    82 ms  xxx.xxx.xxx.128
16    75 ms    80 ms    81 ms  xxx.xxx.xxx.249
17    81 ms    78 ms    80 ms  xxx.xxx.xxx.250
18    82 ms    80 ms    77 ms  xxx.xxx.xxx.2
19   102 ms   101 ms   100 ms  xxx.xxx.xxx.128
20   101 ms   100 ms    98 ms  xxx.xxx.xxx.249
21    97 ms    98 ms    99 ms  xxx.xxx.xxx.250
...

What are the basic steps for troubleshooting this error?

networking ping tcp ttl