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Questions tagged [ttl]

Time To Live is a mechanism to prevent messages from traversing the network indefinitely

Every IP packet has a Time To Live, it is a counter that gets deducted when it passes a router. It prevents a packet from traversing the network endlessly. If the packets TTL reaches 0 it gets discarded. TTL can be a timestamp or a counter.

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How do I set a varnish response TTL dynamically?

my php script is sending a header X_Cache_ttl: 1h and in my varnish config file I have sub vcl_fetch { if(beresp.http.X-Cache-ttl){ set beresp.ttl = beresp.http.X-Cache-ttl; } } but the line with the set command is causing…
DiverseAndRemote.com
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How does Varnish deal with running out of storage?

I am using Varnish 3.0.3 (the latest as of this writing) with more or less the default install, using the following for storage: # # Cache file location VARNISH_STORAGE_FILE=/var/lib/varnish/varnish_storage.bin # # # Cache file size: in bytes,…
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Is there a standard time duration before DNS caches are cleared?

Is there a standard time duration before DNS caches are cleared, so that if a distracted operator or stuck key turns a TTL of 86400 into 864000000 you don't end up with an authoritative resource record or even entire DNS zone whose changes won't be…
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Small TTL values

What is a TTL in DNS? What is the advantage of having small TTL?
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Best CNAME TTL strategy for fallover switching

I've recently been thinking about the TTL of our DNS. We have A records for our servers and then CNAME records for the customer facing names. The www.example.com CNAME points to server-01.example.com for example. In the event of a failure we have…
Phil Hannent
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AWS Route 53 alias-record change takes too long

I have setup a stack in AWS Cloudformation, which is up and running. The stack contains an ELB (load balancer) and a few EC2-instances. When we do a new deployment of our application, we build a new environment and delete the old one. Therefore, we…
dbroeks
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My TTL changing over every packetand I don't know why

Recently I discovered that some pings sent to me were giving a TTL error. When someone pings my computer, it shows a different TTL value for every packet. For example, ping.eu shows that: --- PING 78.188.216.242 (78.188.216.242) 56(84) bytes of…
Burak Tamtürk
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How network devices affect TTL

When I do a ping, I can see the TTL value for each packet. For every router that I insert in between my computer and the router that connects to the internet, the TTL value goes down by one. However, inserting a switch or a hub does not have any…
Wintermute
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Internal DNS TTLs

Four-site company using Windows Domain and DNS servers. Minimum of one DC/DNS server per site. One site is HQ and hosts most companywide servers and services. DNS records for Windows servers are allowed to register instead of static. Critical…
Tedwin
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Big Trouble with (I think) Outlook X500 addressing

I moved a small client from one hosted Exchange server (Microsoft Office 365) to another (Intermedia.net). Some emails from External senders to the users on the new server host are undeliverable, bouncing off the OLD server w/ no relay errors. It…
Joshua Marshall
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Lowering TTL on nameserver, not registrar, then changing nameservers?

A client website has their domain name registered at GoDaddy. This domain points to Wix.com's nameservers. I've lowered the TTL in wix to 1 hour. However, when we go live we'll be switching the nameservers themselves (with Godaddy). When a zone…
Radley Sustaire
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Outlook.com DNS so slow, postfix times out

I'm trying to send e-mails to for example: postmaster@grassvalley.com and postmaster@jorssen.net.bmw.be. In both cases these are Outlook mailboxes. Postfix replies with: (when ipv6 enabled): 06F908112E 606 Thu Jun 19 10:20:40 …
Tuinslak
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Windows Server 2008 R2 DNS - Syncronizing changes to TTL

I apologize if this has been asked. My searches have not been successful. If I have 2 DNS servers in my Domain and add an A record to 1 server, that record is successfully propagated to the second server. If, however, I edit the TTL for a specific…
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Moving DNS hosting for Active site to Route 53 - with G Suite MX TTL of 1 week

I am following the steps outlined in this AWS guide to transfer my domain hosting from GoDaddy to AWS. Step 4 requires me to lower TTL for my existing NS Record to avoid downtime if I encounter issues. However, I see I also have MX records for my…
cash22
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possible to see remaining DNS negative cache for domain?

For normal DNS lookups, one can use Dig to get an answer including the remaining TTL for a DNS record. If that answer is from a cache, the TTL will "count down" until the next authoritative query, and the remaining time until that query will appear…
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